EnC: Add a code action that updates all call-sites of a method with changed signature

[tmat]

When a method signature is changed during EnC/Hot Reload, we update the existing method to throw MethodMissingException and add method with the new signature. The callers are not updated unless the user explicitly makes changes to them.

In some cases we will be able to emit a trampoline to the old method that calls the new method, but not in all cases.

The EnC analyzer could squiggle the updated method signature and provide a code action that finds all call-sites of the previous version of the method and updates their containing methods. If executed before the signature change is applied it would be part of the change. Otherwise, it would trigger a new update.

[tmat]

@davidwengier FYI