Fixes#4976.
Fixes KEYMAN-WINDOWS-2K.
Fixes KEYMAN-WINDOWS-3F.
Fixes KEYMAN-WINDOWS-5A.
Fixes KEYMAN-WINDOWS-3E.
This fix reworks keymanx64's lifecycle, moving responsibility for
process shutdown from keyman.exe to keymanx64.exe.
This eliminates the need for interprocess communication, and simplifies
the startup and shutdown of keymanx64.exe. Removing this means that we
can more safely handle situations where two instances of keymanx64 may
be started, as one of them will rapidly terminate when it discovers that
its parent process has disappeared.
Fixes#4988.
Fixes KEYMAN-WINDOWS-3F.
This relates to #4976 and is a stop-gap until we implement that. It will
reduce the number of reported errors (both to us and the end user) but
does not address the core issue, which requires a more significant
refactor.
We used the 'Started' event when testing Sentry integration. We no
longer need it, but I left it in as commented code so we can re-enable
if/when we do Sentry updates in the future and need to re-test.
