This reverts commit fcf7182.

### Reverts PR
Reverts #18354
Reverts #18490
Reverts #18402

### Issues fixed
<!-- Issues that will be closed by reverting, i.e. the issues introduced
via the PR getting reverted -->
Fixes #18519 

### Issues reopened
<!-- Issues that will be re-opened by reverting, i.e. the issues that
were fixed via the PR getting reverted -->
Reopens #15905

### Reason for revert
The current implementation breaks NVDA remote and breaks add-on APIs

### Can this PR be reimplemented? If so, what is required for the next
attempt
- use truststore.SSLContext directly rather than source code wide
injections. It is
[unclear](https://truststore.readthedocs.io/en/latest/#using-truststore-with-requests)
how to do that with requests. [this SO answer suggestions an
option](https://stackoverflow.com/a/78265028).
- perform the changes in an API breaking release, encourage authors to
use `inject_into_ssl, extract_from_ssl` where required

…8528)

Fixes #15905
Reimplements #18354, #18402, #18490

### Summary of the issue:
When trying to download an add-on from the add-on store in certain
environments such as corporates, the download fails due to the machine
not trusting the root certificate of the add-on source.

This can be caused by two issues:

* the requests library using certifi rather than the system root
certificates
* the system root certificates not trusting the add-on download source

When performing an update check, we update windows root certificates if
our certificate is invalid or out of date.

### Description of user facing changes:
NVDA should more reliably trust request endpoints using windows root
certificates. e.g. accessing the add-on store in a corporate
environment.

### Description of developer facing changes:
requests and similar libraries now has truststore injected into it

### Description of development approach:
This pull request improves how NVDA handles SSL/TLS certificate
verification, particularly for HTTPS requests and add-on downloads. It
ensures that the application uses the Windows root certificate store
instead of the Python default (certifi), provides a fallback mechanism
to update root certificates when encountering untrusted certificates,
and enhances user interaction when certificate errors occur during
add-on downloads. Additionally, shared networking logic has been
refactored and centralized for maintainability.

**Certificate Verification and Networking Improvements:**

* Added the `truststore` dependency and injected it at startup so that
all `requests` HTTP calls use the Windows root certificate store instead
of certifi, improving compatibility in corporate and managed
environments. (`pyproject.toml`, `source/core.py`)
[[1]](diffhunk://#diff-50c86b7ed8ac2cf95bd48334961bf0530cdc77b5a56f852c5c61b89d735fd711R32-R33)
[[2]](diffhunk://#diff-dbe862167add4fbe8e502757f792615f714c7603621c03d0c60c08a6a613ad68R34)
[[3]](diffhunk://#diff-dbe862167add4fbe8e502757f792615f714c7603621c03d0c60c08a6a613ad68R680-R683)
* Introduced a new `utils/networking.py` module that centralizes logic
for fetching URLs, handling certificate verification errors, and
updating Windows root certificates. This includes helper functions like
`_fetchUrlAndUpdateRootCertificates`, `_getCertificate`, and
`_updateWindowsRootCertificates`. (`source/utils/networking.py`)

**Add-on Store and Update Check Enhancements:**

* Updated add-on store and update check logic to use the new
`_fetchUrlAndUpdateRootCertificates` function, ensuring robust handling
of certificate verification failures and automatic root certificate
updates when necessary. (`source/addonStore/dataManager.py`,
`source/updateCheck.py`)
[[1]](diffhunk://#diff-9fd9bbb610bac3157554c0876fba6ea3475383ea9de36c2101ba1127cf5189e5R30)
[[2]](diffhunk://#diff-9fd9bbb610bac3157554c0876fba6ea3475383ea9de36c2101ba1127cf5189e5L127-R128)
[[3]](diffhunk://#diff-9fd9bbb610bac3157554c0876fba6ea3475383ea9de36c2101ba1127cf5189e5L138-R143)
[[4]](diffhunk://#diff-69aa1f3d46c308cf71c96483fd196eb49d6348727ab1953f834b1974ff031a43R68-R76)
[[5]](diffhunk://#diff-69aa1f3d46c308cf71c96483fd196eb49d6348727ab1953f834b1974ff031a43L241-R245)
* Improved the add-on download process to prompt the user when
encountering an untrusted certificate, displaying the SHA256 fingerprint
and allowing the user to trust and install the root certificate if
appropriate. (`source/addonStore/network.py`)
[[1]](diffhunk://#diff-097e46da59cc87eb0100bd63db7cfe32c7095ec66cf4be02d5dc84f28682ac7eL239-R297)
[[2]](diffhunk://#diff-097e46da59cc87eb0100bd63db7cfe32c7095ec66cf4be02d5dc84f28682ac7eR314-R315)

**Codebase Cleanup and Refactoring:**

* Removed duplicate and now-unnecessary certificate update logic from
`updateCheck.py` and centralized all certificate handling in
`utils/networking.py`. (`source/updateCheck.py`)
* Updated variable naming and improved code clarity in the add-on
download logic. (`source/addonStore/network.py`)
[[1]](diffhunk://#diff-097e46da59cc87eb0100bd63db7cfe32c7095ec66cf4be02d5dc84f28682ac7eL239-R297)
[[2]](diffhunk://#diff-097e46da59cc87eb0100bd63db7cfe32c7095ec66cf4be02d5dc84f28682ac7eR314-R315)
[[3]](diffhunk://#diff-097e46da59cc87eb0100bd63db7cfe32c7095ec66cf4be02d5dc84f28682ac7eL268-R324)
[[4]](diffhunk://#diff-097e46da59cc87eb0100bd63db7cfe32c7095ec66cf4be02d5dc84f28682ac7eL278-R334)
[[5]](diffhunk://#diff-097e46da59cc87eb0100bd63db7cfe32c7095ec66cf4be02d5dc84f28682ac7eL290-R346)

### Testing strategy:

- [x] Get user testing from #15905
- [x] Smoke test using add-on store
- [x] Smoke test update check

### Known issues with pull request:
None

---------

Co-authored-by: Sascha Cowley <16543535+SaschaCowley@users.noreply.github.com>