[transfer-non-sendable] Teach SILIsolationInfo how to handle "look through instructions" when finding actor instances.

[gottesmm]

From the perspective of the IR, we are changing SILIsolationInfo such that
inferring an actor instance means looking at equivalence classes of values where
we consider operands to look through instructions to be equivalent to their dest
value. The result is that cases where the IR maybe puts in a copy_value or the
like, we consider the copy_value to have the same isolation info as using the
actor directly. This prevents a class of crashes due to merge failings. Example:

actor MyActor {
  init() async {

  init(ns: NonSendableKlass) async {
    self.k = NonSendableKlass()
    self.helper(ns)
  }

  func helper(_ newK: NonSendableKlass) {}
}

Incidently, we already had a failing test case from this behavior rather than
the one that was the original genesis. Specifically:

1. If a function's SILIsolationInfo is the same as the isolation info of a
   SILValue, we assume that no transfer actually occurs.

2. Since we were taking too static of a view of actor instances when comparing,
   we would think that a SILIsolationInfo of a #isolation parameter to as an
   argument would be different than the ambient's function isolation which is also
   that same one. So we would emit a transfer non transferrable error if we pass in
   any parameters of the ambient function into another isolated function. Example:

actor Test {

  @TaskLocal static var local: Int?

  func withTaskLocal(isolation: isolated (any Actor)? = #isolation,
                     _ body: (consuming NonSendableValue, isolated (any Actor)?) -> Void) async {
    Self.$local.withValue(12) {

      // We used to get these errors here since we thought that body's isolation
      // was different than the body's isolation.
      //
      //  warning: sending 'body' risks causing data races
      //  note: actor-isolated 'body' is captured by a actor-isolated closure...
      body(NonSendableValue(), isolation)
    }
  }
}

rdar://129400019

[gottesmm]

@swift-ci smoke test

[gottesmm]

While doing this list of look through, I wanted to see how having consuming/borrowing as actor self worked... and I found in the consuming case we crashed. I am going to fix that in a different PR. But I thought it was worth putting in tree.

[ktoso]

Nice catch, thanks for followup then as well :)

[ktoso]

LGTM, thanks!