5c14c528c [Windows] Hide Win32 API of the keyboard system behind ifdef (flutter/engine#24677) (#76931)

This reverts commit f8cd24de in an attempt to re-land it.

There are no changes in this PR from #74373, since it only failed Google internal tests, and we think that the solution involves updating those tests instead of changing this code.

This reverts commit 24bf6b81.

3dbf9638d Roll Skia from 9fe866174147 to a42c6192ff67 (12 revisions) (flutter/engine#24646) (#76841)

aead5acb3 [extension_google_sign_in_as_googleapis_auth] Migrate to null safety (flutter/plugins#3642) (#76878)

* 4f660da97 Roll Dart SDK from 63c6585d8499 to 6b7054122356 (1 revision) (flutter/engine#24625)

* 25887bc9b Roll Skia from e79bb32365ea to 4ac9aadd306b (4 revisions) (flutter/engine#24630)

* 1bdf5d328 TextStyle level leadingDistribution (flutter/engine#24025)

* c4678d65a Fix input flow event logic (flutter/engine#24526)