auto: increment master version to 15.0.75

fix(linux): Add libglib2.0-bin to keyman Depends 🍒

Fixes #5344

(cherry picked from commit 12e2c4c2)

feat(linux): Add support for impish (Ubuntu 21.10)

feat(common/core/web): engine correction-prep optimizations

fix(android): fixes application of nextlayer for subkeys with customized layer setting

auto: increment master version to 15.0.74

fix(linux): Improve error handling if `lang_tags_map.py` is missing

If the developer forgot to run `make` to create `lang_tags_map.py`
we now print a message instead of reporting to Sentry.

Fixes #5343

feat(linux): Auto-generate reference help

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

chore(windows): add engine test framework

This is a rudimentary start to having unit tests for keyman32.

At present, it will build only in win32/debug and requires you
to manually run make -DDEBUG beforehand. The tests currently
run in Visual Studio and are not integrated.

auto: increment master version to 15.0.73

For auto-generating help files we need `buildtools`, so we can't
exclude it from source package. Also, we now include our version
of `help2man`, so we no longer need it as a build dependency,
but instead directly depend on `perl`.

During a package build we don't have access to `scripts/reconf.sh`.
However, we don't really need it since we already ran it before.
This change adds a `--no-reconf` flag that allows skipping
`reconf.sh`.

change(ios): setText now uses JSON serialization

refactor(web): osk key highlighting/preview behavior

refactor(web): OSK key source-code reorganization

chore(linux): Build also on riscv64 to facilitate migration on Ubuntu 🍒

fix(windows): restore endpoints for interface stability

fix(mac): kmp.inf is windows-1252

fix(mac): .kmx max file version is now 0x0E00 (14.0)

Fixes #5316.

Keyman for macOS did not recognise the updated version number 0x0E00,
which is version 14.0. There are no changes to the file format which
impact Keyman for macOS -- the only change is support for notany and
context for Keyman Engine for Web.