Updates the implementation of escape analysis rules for method invocation to match the recent spec changes - see #62791.

The updated rules are in effect when compiling with a corlib that includes System.Runtime.CompilerServices.RuntimeFeature.ByRefFields, or when compiling with -langversion:11 or higher.

Method invocation:

For a given argument a that is passed to parameter p:

1. If p is scoped ref then a does not contribute ref-safe-to-escape when considering arguments.
2. If p is scoped then a does not contribute safe-to-escape when considering arguments.

A value resulting from a method invocation e1.M(e2, ...) is safe-to-escape from the smallest of the following scopes:

1. The calling method
2. The safe-to-escape contributed by all argument expressions
3. When the return is a ref struct then ref-safe-to-escape contributed by all ref arguments

A value resulting from a method invocation ref e1.M(e2, ...) is ref-safe-to-escape the smallest of the following scopes:

1. The safe-to-escape of the rvalue of e1.M(e2, ...)
2. The ref-safe-to-escape contributed by all ref arguments

Method arguments must match:

For any method invocation e.M(a1, a2, ... aN)

1. Calculate the safe-to-escape of the method return (for this rule assume it has a ref struct return type)
2. All ref or out arguments of ref struct types must be assignable by a value with that safe-to-escape. This applies even when the ref argument matches a scoped ref parameter.

The PR also includes a change to treat ref parameters to ref struct types as scoped ref by default - see #62691.

Fixes #62791
Fixes #62691
Fixes #63016