[READY] Make C# completer consistent with other completers regarding GoToDocumentOutline #610

Job	Run time
C++ Lint	5m 58s
ubuntu-20.04 - C++ Benchmark	1m 54s
Windows MSVC 17 x64 - C++ Benchmark	3m 56s
ubuntu-20.04 - test run	1m 9s
Windows MSVC 17 x64 - test run	2m 17s
macos-12 - C++ Benchmark	2m 57s
Windows MSVC 17 x86 - test run	1m 52s
macos-12 - test run	1m 37s
Windows MSVC 16 x64 - test run	2m 0s
ubuntu-20.04 - with Clang compiler - test run	1m 0s
ubuntu-20.04 - without libclang completer - test run	1m 3s
	25m 43s

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