* Generate friendly syntax for nint/nuint

* Opportunistic change

* Use ternary and add comments

* Fix formatting

* Remove NativeIntegerAttribute in generated source

* Fix classification for nint/nuint

The CompareAllBytesEmitted tests need to be disabled on CoreCLR due to
a flakiness issue.

* Enable nullable reference types for SymbolExtensions

* Add missing annotation

Fix a bug in conversion classification that improperly hides a switch expression conversion when there is a built-in explicit conversion (#42339)

This bug results in the compiler crashing or producing bad code in some scenarios.
Fixes #42331

There are two problems here, the first of which is the most important.

First, certain data flow analyses use "normalization" to adjust an existing
state variable for more variables declared after that state was created.
The default behavior is to extend that state to the "top" state, meaning
the starting state for that data flow analysis. This is usually the
right extension. However, some analysis requires extending the
variables the other way, to the bottom state. This PR adds functionality
for that customization.

The second problem is that data flow for local functions may include
variables that are not captured. This is by filtering the transfer function
to only include captured variables.

Fixes fixes #41600

IDE layer uses a special "CompilerDiagnosticAnalyzer" for reporting compiler diagnostics, which leads to analyzer bulk configuration getting applied to compiler diagnostics reported from this analyzer in the IDE. This change ensures compiler diagnostics are explicitly skipped from analyzer bulk configuration.

Fixes #42116

in definite assignment analysis.

This reverts commit c2a7ed11.

Fixes #41682
Fixes #40326

CastUp has a static type requirement so it can avoid a type check.

Fixes #41631