Handle RunClassConstructor with nonreflectable cctor (#62947)

Handle RunClassConstructor with nonreflectable cctor (#62947)

This is now getting hit in #62927, so it's somewhat more urgent. (The feature switches from the SDK put us into the situation that triggers this bug around `RunClassConstructor` on an otherwise unused type.)

Fixes dotnet/runtimelab#987.

Remember what class constructor contexts we saw during scanning phase and if the owning type is also generated, assume `RunClassConstructor` could be used and ensure the cctor context is also generated in the compilation phase.

This is somewhat less precise, but introducing a new node type for "a type used with `RunClassConstructor`" that dataflow analysis could report doesn't seem worth it.