…55053)

This commit adds support for extracting initializer API functions.
Initialixer API functions are functions conceptually that can are
intended to be used as class member initializers.

Angular started introducing a few of these for the new signal
APIs, like `input`, `model` or signal-based queries.

These APIs are currently confusingly represented in the API docs because
the API extraction:

- does not properly account for call signatures of interfaces
- does not expose information about sub-property objects and call
  signatures (e.g. `input.required`)
- the docs rendering syntax highlighting is too bloated and confusing
  with all types being included.

This commit adds support for initializer API functions, namely two
variants:

- interface-based initializer APIs. e.g. `export const input:
  InputFunction`- which is a pattern for `input` and `input.required`.
- function-based simpler initializer APIs with overloads. e.g.
  `contentChildren` has many signatures but doesn't need to be an
  interface as there are no sub-property call signatures.

PR Close #55053

This commit ensures that extracted initializer API functions are
showing up in angular.dev and can be filtered.

PR Close #55053

…ev support (#55053)

This commit improves the API documentation for `input` after
we added support for initializer APIs in angular.dev docs generation.

Changes:

- Rename `ReadT` to `T`. This conceptually makes it easy to talk about
  inputs of type `T` if there is no transform involved. The common case.
- Rename `WriteT` to `TransformT`. This makes it clear that this is the
  type that the "transform" needs to handle.
- Improves the "overall" description of the input function so that it
  can be shown as a general overview for the API site.
- Improves usage notes to be a little more helpful, yielding more useful
  content in the API docs usage notes section.
- Add short JSDoc description for each individual overload.

PR Close #55053

Improves the API documentation for `model`, similarly to how
we updated the `input` function.

PR Close #55053

This improves the API documentatino for `output` in angular.dev,
similar to how we improved the API for `input`.

Angular.dev can now show these documentation entries more
readable if annotated explicitly as initializer API.

Note: output API is short enough that we want to include
the types in the code snippet previews.

PR Close #55053

…55053)

Similar to `input`, `model`, `output`, the query initializer APIs are
also explicitly denoted as such. This allows angular.dev to display them
more readable and compactly.

PR Close #55053

…extraction (#55053)

This commit adds support for ignoring specific doc entries when
extracting doc entries. This allows us to drop e.g. `InputFunction` from
the API docs, given that the `input` API entry holds all the relevant
information.

`InputFunction` only exists for type purposes in the `.d.ts`.

PR Close #55053