* dotnet/features/ioperation: (159 commits)
  Fix a unit test
  Refactor code hardcode CaseClauseKind in constructors
  Add some more tests to verify statement filtering
  Make IOperation.HasErrors internal
  Address PR feedback and add basic unit tests for changed APIs
  Address some minor TODO comments in features/ioperation branch
  Remove CaseClause related Operation kinds which are already represented through CaseKind
  Address PR feedback and add more tests
  Fix unit test failures from merge
  fixed ordering
  Address feedback from Aleksey and generate a dynamic member reference expression for a bound method group that is a child of dynamic invocation
  Move test so it's not between two related tests
  Update languae feature status. (#22037)
  guard us from build errors which are marked as CS or VBXXXX for a linked file that doesnt belong to current solution we have.
  Remove context (enclosing type name) from C# parser. (#18940)
  Fix unit test failures
  Address PR feedback and handle few more statement cases in bound block filter
  Address some more review feedback
  Delete the EditorFeatures.Next project
  Merge Structure tagging from EditorFeatures.Next to EditorFeatures
  ...

Make certain untested/not yet design approved IOperation APIs internal

Remove CaseClause related Operation kinds which are already represent…

Address some minor TODO comments in features/ioperation branch

Addresses https://github.com/dotnet/roslyn/issues/22124.

Add IOperation APIs for Dynamic invocations and indexer access

See https://github.com/dotnet/roslyn/issues/21385#issue-248857857

I also found that Range and Relational case clause have no tests in VB. Additionally, I also marked all OperationAnalyzerTests with CompilerTrait attribute so they don't get skipped in local trait based testing.
Fixes #22129

Merge master to features/ioperation

Changes to the IOperation API shape for loop statements

Update the 'add named arg' refactoring to support only adding to the current argument (for C# 7.2 and above).

guard us from build errors which are marked as CS or VBXXXX for a lin…

Merge master to features/ioperation

Disable useUserOverride in CultureContext

Remove InitialTargets=MakeCompilerScriptsExecutable

Merge `private protected` feature into master for C# 7.2 and VB 15.6.

Address feedback from Aleksey and generate a dynamic member reference expression for a bound method group that is a child of dynamic invocation

Merge master into privateProtected branch

Fixed Inline Temporary Variable refactoring

Updating some nuspec to list the correct framework requirements and dependencies.

Fix IArgument.InConversion/OutConversion