Fix some file associations

[Colengms]

Aligns some hard-coded default file associations with the defaults on the native side. (There is a separate native PR for fixes there).

Fixes a bug where .C may be considered a C source file (uppercase implies C++).

Correctly considers .i a C source file, and .ii a C++ source file. Added missing header type: .tlh, .tli

Moves .tcc to the list of header files instead of source files.

Not addressed by this PR: These functions should also consider the contents of files.assocations (at least for source file types, as that does not distinguish between headers and sources).

[bobbrow]

Correctly considers .i a C source file,

Is this universally true? I recently preprocessed a .cpp file with MSVC and it spit out a .i for me.

[Colengms]

Correctly considers .i a C source file,

Is this universally true? I recently preprocessed a .cpp file with MSVC and it spit out a .i for me.

It looks like MSVC incorrectly copied the convention from GCC/clang, and doesn't properly use .ii for C++ sources. However, if you look at the native PR, at the changes in settings.h, you'll see that we were already considering .i a C file. (Apparently because VS Code itself considers .i a C source file, which you can confirm by opening one).

[bobbrow]

It looks like MSVC incorrectly copied the convention from GCC/clang, and doesn't properly use .ii for C++ sources. However, if you look at the native PR, at the changes in settings.h, you'll see that we were already considering .i a C file. (Apparently because VS Code itself considers .i a C source file, which you can confirm by opening one).

I'm not particularly worried about it since I don't think there are any existing bugs asking for different behavior. It seems to be an uncommon scenario.