* web: fix file upload form name mismatch and modal submit promise handling

Fixes the following error:

FileUploadForm.ts:74  POST http://authentik.localhost:9000/api/v3/admin/file/ 405 (Method Not Allowed)
(anonymous) @ fetch.ts:81
fetchApi @ runtime.ts:206
await in fetchApi
request @ runtime.ts:136
await in request
adminFileCreateRaw @ AdminApi.ts:191
adminFileCreate @ AdminApi.ts:206
send @ FileUploadForm.ts:74
submit @ Form.ts:363
(anonymous) @ ModalForm.ts:54
handleEvent @ lit-html.ts:2109
n @ helpers.ts:117Understand this error
Form.ts:403 authentik/forms: API rejected the form submission due to an invalid field that doesn't appear to be in the form. This is likely a bug in authentik. {detail: 'Response returned an error code'}
(anonymous) @ console.ts:39
(anonymous) @ Form.ts:403
Promise.catch
submit @ Form.ts:376
(anonymous) @ ModalForm.ts:54
handleEvent @ lit-html.ts:2109
n @ helpers.ts:117Understand this error
runtime.ts:140 Uncaught (in promise) ResponseError: Response returned an error code
    at mR.request (runtime.ts:140:15)
    at async mR.adminFileCreateRaw (AdminApi.ts:191:26)
    at async mR.adminFileCreate (AdminApi.ts:206:9)

- align file upload rename field with api name so validation errors map correctly
-improve custom filename extension logic to avoid double or incorrect  extensions
- prevent unhandled promise rejections from modal submit click handler and show  missing-form errors to users

* rev

* wip

* Update ModalForm.ts

Signed-off-by: Dominic R <dominic@sdko.org>

* scope better

* fix what it validates against

---------

Signed-off-by: Dominic R <dominic@sdko.org>