csharp: sync `v1.1.0` from John-Paul-R/FlexVer

[John-Paul-R]

This PR deals with some build/packaging details, and reworks the comparer implementation to be faster and make no heap allocations.

Benchmark results, using the version strings in the test harness:

Method	Mean	Error	StdDev	Gen0	Allocated
CompareAll_New	6.248 us	0.1228 us	0.2245 us	-	-
CompareAll_Existing	30.432 us	0.6077 us	1.1112 us	0.3967	33672 B

NuGet listing from these build changes: https://www.nuget.org/packages/FlexVer

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