Revert "Remove unused entries in InputMethodSettings API."

This reverts commit 67bc5741985963e7b9b470c40cb3f5776cd9262f.

Reason for revert:
Many bot failures for tast.inputs.VirtualKeyboard* tests

See first failing build below
https://ci.chromium.org/ui/p/chrome/builders/ci/chromeos-betty-chrome-dchecks/4686/overview

Original change's description:
> Remove unused entries in InputMethodSettings API.
>
> This private API is meant for exclusive use by CrOS 1P Virtual
> Keyboard (VK) + IME extension (in internal repo). It doesn't need
> to declare typings for all data entries; only those needed by CrOS
> 1P VK+IME extension are required.
>
> Indeed, it's already the case that these do not include all available
> entries, while many entries are declared here but no longer used by
> CrOS 1P VK+IME extension, because they're obsolete, broken, or simply
> not needed. Those unused entries are being removed in this CL.
>
> Unused or unnecessary entries incur maintenance cost, as they must
> always match precisely what's defined by CrOS Settings UI and
> actually available in CrOS Prefs storage.
>
> Bug: None
> Change-Id: I5e0e0e20b1d0ac5c9d1e792cdbc270d0e6b9154b
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/7140820
> Reviewed-by: Jimmy Gong <jimmyxgong@chromium.org>
> Reviewed-by: Darren Shen <shend@chromium.org>
> Commit-Queue: Bao-Duy Tran <tranbaoduy@chromium.org>
> Cr-Commit-Position: refs/heads/main@{#1546968}

Bug: None
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Change-Id: Iac974f62e57353bfbbf96a78c3190861813b3b56
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/7171540
Auto-Submit: Tom Lukaszewicz <tluk@chromium.org>
Commit-Queue: Tom Lukaszewicz <tluk@chromium.org>
Owners-Override: Tom Lukaszewicz <tluk@chromium.org>
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Cr-Commit-Position: refs/heads/main@{#1547265}
NOKEYCHECK=True
GitOrigin-RevId: a76a70ef35fa12d790fe01fab7e4e93bf456fcdf