[GDBJIT] Specify C# language in DWARF debug information (dotnet/coreclr#13720)

[GDBJIT] Specify C# language in DWARF debug information (dotnet/coreclr#13720)

* [GDBJIT] Specify C# language in DWARF debug information

To correctly support C# language in lldb DWARF debug information
should contain correct information about language.

Now we use 0x9e57 constant for specify C# language.

* [GDBJIT] Introduce FEATURE_GDBJIT_LANGID_CS

If this feature is set gdbjit will use 0x9e57 as c# lang id,
otherwise it will use DW_LANG_C89.

Commit migrated from https://github.com/dotnet/coreclr/commit/18ab3567e2ea6e2a385527bb247b0eec32a995cb