fix(windows): cherry pick modifier event is always serialized 🍒

Co-authored-by: Marc Durdin <marc@durdin.net>

wm_keyman_keyevent and wm_keyman_modifierevent have been convert to use
the WM_USER message range and no longer global message

Co-authored-by: Marc Durdin <marc@durdin.net>

PR #7449 added modifier event to make ensure modifer events
where sent to the serializer even if the key stroke was determined
the key stroke did not need seralizing. However, a logic error was made
trying to use the exiting 'Flag' however this was not set in the
!UseCachedHotkeyModifierState case. This change adds helper function
to simply check if the key is a modifier key and send it to the
event seralizer in that case. Separating from the other logic which
is more concerned with handling hotkeys.

chore(linux): Update debian changelog

auto: increment stable-15.0 version to 15.0.275

fix(windows): lower case filenames for projects for stable-15.0

fix(android/engine): Use FLAG_IMMUTABLE for PendingIntent for Android S+ 🍒

chore(linux): Update debian changelog

auto: increment stable-15.0 version to 15.0.274

chore(android): Update Target SDK Version to 31 🍒

fix(windows): base layout support in Keyman Core 🍒

While Keyman Core already supported the base layout flags, they were not
being passed in from Keyman Engine for Windows. This meant that any
rules that used `baselayout` would fail, such as in sil_ipa with AltGr+0
for }

https://github.com/keymanapp/keyboards/blob/0bf72bed74f563f823b1af002f6a8ccef8510ebf/release/sil/sil_ipa/source/sil_ipa.kmn#L348-L350

This patch adds support for the following properties:

* KM_KBP_KMX_ENV_BASELAYOUT: the legacy base layout name, e.g. kbdus.dll
* KM_KBP_KMX_ENV_BASELAYOUTALT: the BCP 47 base layout name, e.g. en-US
* KM_KBP_KMX_ENV_SIMULATEALTGR: whether the user has selected to emulate
  AltGr with Ctrl+Alt, for example on laptops without a right alt key.
* KM_KBP_KMX_ENV_BASELAYOUTGIVESCTRLRALTFORRALT: whether the system base
  layout in use generates Ctrl+RAlt when RAlt is pressed, which can be
  true for many European system layouts. This is necessary when
  associating the keyboard with a European language because the base
  keyboard becomes the language's default keyboard, rather than kbdus.

chore(linux): Update debian changelog

fix(android/engine): Use IME package name if query permission denied 🍒

chore(linux): Update debian changelog

chore: Add #7554 to HISTORY.md

auto: increment stable-15.0 version to 15.0.273

Merge pull request #7538 from keymanapp/fix/developer/cherry-pick/7529-enforce-us-layout-for-debugger

fix(developer): Use US base layout for debugger 🍒

fix(ios): iPad was not recognised as tablet device 🍒

Fixes #7517.

Cleans up the setDeviceType code which was attempting to set the device
type far too late in the init sequence, and moves responsibility for
detection from kmwembedded.ts to ios-host.ts, as this device test is
iOS-specific.

fix(android/engine): Dismiss key previews and subkeys on multi-touch 🍒

fix(android/engine): Dismiss subkeys when hiding keyboard 🍒

fix(developer): handle LControl being set by Windows when AltGr pressed 🍒