Fixes#7216.
The warning message 0x209A 'The rule will never be matched because its
key code is never fired.' was being generated multiple times for a
single line because the `JavaScript_Key` function it is generated by is
used for various purposes.
This PR keeps a cache of reported key rules to ensure that the message
is reported only once for a given key rule, and also improves the
reporting to clarify which specific key is unreachable, which makes it
easier to diagnose when using `any(k)` style messages, for example:
```
lao_phonetic.kmn (237): Warning: 209A The rule will never be matched for key 'ñ' because its key code is never fired.
```
This also reduces the warning to a hint, as this should not be a
blocking issue for a keyboard, rather just a place the keyboard author
can tidy up.
If `-no-compiler-version` is specified, then we skip the embedding of
the `TSS_COMPILEDVERSION` and `TSS_KEYMANCOPYRIGHT` stores. This is
intended for use with regression test builds of keyboards when we want
to verify changes to the compiler.
This patch introduces the new export `SetCompilerOptions` in kmcmpdll,
which should make it easier to include new options like this in future
versions.
