Added workspace folder tests

[david-driscoll]

Ran into a scenario where I need to "overload" the magic, so this also normalized initilaize/initilaized/startup handling

[codecov]

Codecov Report

Merging #279 into master will increase coverage by 28.13%.
The diff coverage is 89.81%.

@@             Coverage Diff             @@
##           master     #279       +/-   ##
===========================================
+ Coverage   37.94%   66.08%   +28.13%     
===========================================
  Files         413      415        +2     
  Lines       13069    13274      +205     
  Branches     1548     1555        +7     
===========================================
+ Hits         4959     8772     +3813     
+ Misses       7717     4216     -3501     
+ Partials      393      286      -107     

Impacted Files	Coverage Δ
src/Dap.Shared/DebugAdapterHandlerCollection.cs	80.91% <ø> (-0.15%)	⬇️
...col/Workspace/IDidChangeWorkspaceFoldersHandler.cs	0.00% <ø> (ø)
...er/Configuration/DidChangeConfigurationProvider.cs	22.09% <25.00%> (-0.53%)	⬇️
src/Server/LanguageServerWorkspaceFolderManager.cs	83.07% <60.00%> (+21.78%)	⬆️
src/Dap.Shared/DebugAdapterEventingHelper.cs	64.28% <64.28%> (ø)
src/Protocol/LanguageProtocolEventingHelper.cs	64.28% <64.28%> (ø)
src/Client/LanguageClient.cs	90.95% <93.33%> (+21.25%)	⬆️
src/Dap.Client/DebugAdapterClient.cs	91.58% <95.23%> (+3.06%)	⬆️
src/Dap.Server/DebugAdapterServer.cs	82.87% <96.87%> (+14.20%)	⬆️
src/Server/LanguageServer.cs	81.25% <96.87%> (+29.25%)	⬆️
... and 205 more

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