Add support for /instrument codecoverage for new language features

[ManishJayaswal]

@JohnHamby mentioned that it does not work for all new C# language features.

[ManishJayaswal]

FYI - @JohnHamby @jaredpar @VSadov @jcouv @gafter

[gafter]

We already support instrumentation for

1. the deconstruction declaration statement (currently Instrumenter.InstrumentLocalDeconstructionDeclaration)
2. deconstruction in a for-each (currently Instrumenter.InstrumentForEachStatementDeconstructionVariablesDeclaration)
3. the pattern switch statement (currently Instrumenter.InstrumentPatternSwitchStatement)
4. the new switch when clause (currently Instrumenter.InstrumentPatternSwitchWhenClauseConditionalGotoBody)

These are already implemented for Instrumenter, CompoundInstrumenter, and DebugInfoInjector, and invoked appropriately from the compilers.

Code coverage support will need to be specified and then implemented. I'll set up a meeting to decide what the spec is.

[gafter]

See also #14156

[msJohnHamby]

Just to be sure that there's no confusion, the instrumentation requested here is done by DynamicAnalysisInjector, which is absent from the list of already-enhanced instrumenters mentioned above.

[ManishJayaswal]

FYI @AlekseyTs

[gafter]

The desired behavior is as follows

• For InstrumentLocalDeconstructionDeclaration, it should be instrumented just like any other statement.
• For InstrumentForEachStatementDeconstructionVariablesDeclaration, it should be instrumented the same way as InstrumentForEachStatementIterationVarDeclaration.
• For InstrumentPatternSwitchStatement, it should be handled the same way as InstrumentSwitchStatement.
• For InstrumentPatternSwitchWhenClauseConditionalGotoBody, the ‘when’ clause should be instrumented as if it were a separate statement. There doesn’t appear to be a suitable helper to do that, because the clause isn’t syntactically a Statement, but the instrumentation should do something morally equivalent.