Fix build break where Microsoft.Terminal.Control.dll is empty

[zadjii-msft]

TIL that the <None Include="Foo.def" /> line in our projects is
actually totally meaningless. The important line is the one that's in
cppwinrt.build.pre.props, where we declare

<ModuleDefinitionFile Condition="Exists('$(ProjectName).def')">$(ProjectName).def</ModuleDefinitionFile>

So if you change a project's name, and not the .def file, then the
linker will just not use the .def file at all.

More importantly, this seemingly doesn't matter in debug builds. In a
Debug build, the linker will happily still include WINRT_CanUnloadNow
and WINRT_GetActivationFactory in the exports from the dll, even
without the .def. But in a Release build, the linker is much more
agressive about pruning symbols that aren't referenced, and without
those two, NONE of the symbols are eventually referenced.

This PR fixes Microsoft.Terminal.Control by renaming the .def, and
makes it marginally harder for someone to make the same mistake in the
future.

References

• Regressed in Rename Microsoft.Terminal.TerminalControl to .Control; Split into dll & lib #9472

PR Checklist

• Closes main is horked, bought farm, etc. #9529
• I work here

[zadjii-msft]

@msftbot merge this in 1 minute

[ghost]

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