[READY] Make C# completer consistent with other completers regarding GoToDocumentOutline #612

Job	Run time
C++ Lint	5m 55s
ubuntu-20.04 - C++ Benchmark	1m 46s
ubuntu-20.04 - test run	19m 15s
Windows MSVC 17 x64 - C++ Benchmark	4m 19s
macos-12 - C++ Benchmark	3m 40s
Windows MSVC 17 x64 - test run	30m 55s
macos-12 - test run	23m 22s
Windows MSVC 17 x86 - test run	26m 55s
ubuntu-20.04 - with Clang compiler - test run	19m 2s
Windows MSVC 16 x64 - test run	27m 42s
ubuntu-20.04 - without libclang completer - test run	18m 27s
	3h 1m 18s

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