EnC: Parameter and property analysis

[tmat]

Redesigns parameter and property analysis.

The current approach had issues with method bodies not being properly analyzed when parameters change.
Instead of creating containing symbol changes while analyzing parameters the new approach adds these updates in the set of symbol changes compiled early in the semantic analysis. All non-synthesized members then go through the same body update analysis regardless of whether they were caused by a parameter change, an attribute change or a body change.

Fixes #68708

Other fixes and improvements:

• Allows edits of parameter and return type modifiers. If the actual type doesn't change (e.g. ref changed to out) only an update edit is generated, otherwise delete + insert edits are generated like any other parameter type change.
• Adds more validation to SemanticEdit constructor to catch issues earlier.
• Simplifies handling of deleted events and properties in the compiler. The IDE is now expected to create edits for properties and events when they are deleted or inserted, instead of just for the accessors. The compiler doesn't need to infer these edits.
• Improves diagnostic locations for rude trivia edits.
• Fixes comparison of object and dynamic in signatures.
• Fixes partial method analysis - changes in attributes of both partial definition and implementation parts are now accounted for. Fixes EnC: partial definitions can't be ignored in the analysis since they may contribute attributes, Implements, Handles clauses #54800
• Fixes merging of partial type edits.
• Fixes matching of renamed parameters via SymbolKey. If a parameter can't be matched by name we match by its ordinal.
• Fixes EnC: Renaming a property with initializer doesn't work as expected #69216

[tmat]

@davidwengier PTAL
@cston @dotnet/roslyn-compiler for compiler changes

[cston]

Compiler changes LGTM.

[jaredpar]

@tmat consider retargeting to release/dev17.8 before merging as snap has occurred.