[Distributed] Reimplement distributed call thunks completely in AST (#41616)

* [Distributed] dist actor always has default executor (currently)

* [Distributed] extra test for missing makeEncoder

* [DistributedDecl] Add DistributedActorSystem to known SDK types

* [DistributedActor] ok progress on getting the system via witness

* [Distributed] allow hop-to `let any: any X` where X is DistActor

* [Distributed] AST: Add an accessor to determine whether type is distributed actor

- Classes have specialized method on their declarations
- Archetypes and existentials check their conformances for
  presence of `DistributedActor` protocol.

* [Distributed] AST: Account for distributed members declared in class extensions

`getConcreteReplacementForProtocolActorSystemType` should use `getSelfClassDecl`
otherwise it wouldn't be able to find actor if the member is declared in an extension.

* [Distributed] fix ad-hoc requirement checks for 'mutating'

[PreChecker] LookupDC might be null, so account for that

* [Distributed] Completed AST synthesis for dist thunk

* [Distributed][ASTDumper] print pretty distributed in right color in AST dumps

* wip on making the local/remote calls

* using the _local to mark the localCall as known local

* [Distributed] fix passing Never when not throwing

* fix lifetime of mangled string

* [Distributed] Implement recordGenericSubstitution

* [Distributed] Dont add .

* [Distributed] dont emit thunk when func broken

* [Distributed] fix tests; cleanups

* [Distributed] cleanup, move is... funcs to DistributedDecl

* [Distributed] Remove SILGen for distributed thunks, it is in Sema now!

* [Distributed]  no need to check stored props in protocols

* remote not used flag

* fix mangling test

* [Distributed] Synthesis: Don't re-use AST nodes for `decodeArgument` references

* [Distributed] Synthesis: Make sure that each thunk parameter has an internal name

* [Distributed/Synthesis] NFC: Add a comment regarding empty internal parameter names

* [Distributed] NFC: Adjust distributed thunk manglings in the accessor section test-cases

* cleanup

* [Distributed] NFC: Adjust distributed thunk manglings in the accessor thunk test-cases

* review follow ups

* xfail some linux tests for now so we can land the AST thunk

* Update distributed_actor_remote_functions.swift

Co-authored-by: Pavel Yaskevich <xedin@apache.org>

stdlib/public/Distributed/DistributedActorSystem.swift

@@ -15,7 +15,7 @@ import _Concurrency
 @available(SwiftStdlib 5.7, *)
 public protocol DistributedActorSystem: Sendable {
   /// The identity used by actors that communicate via this transport
-  associatedtype ActorID: Sendable & Hashable & Codable // TODO: make Codable conditional here
+  associatedtype ActorID: Sendable & Hashable & Codable // TODO(distributed): make Codable conditional here
 
   associatedtype InvocationEncoder: DistributedTargetInvocationEncoder
   associatedtype InvocationDecoder: DistributedTargetInvocationDecoder
@@ -106,7 +106,6 @@ public protocol DistributedActorSystem: Sendable {
   /// The returned `DistributedTargetInvocation` will be populated with all
   /// arguments, generic substitutions, and specific error and return types
   /// that are associated with this specific invocation.
-  @inlinable
   func makeInvocationEncoder() -> InvocationEncoder
 
 //  /// Invoked by the Swift runtime when making a remote call.
@@ -344,7 +343,7 @@ func _executeDistributedTarget<D: DistributedTargetInvocationDecoder>(
 // MARK: Support types
 /// A distributed 'target' can be a `distributed func` or `distributed` computed property.
 @available(SwiftStdlib 5.7, *)
-public struct RemoteCallTarget {
+public struct RemoteCallTarget { // TODO: ship this around always; make printing nice
   let _mangledName: String // TODO: StaticString would be better here; no arc, codesize of cleanups
 
   // Only intended to be created by the _Distributed library.
@@ -358,7 +357,7 @@ public struct RemoteCallTarget {
   }
 
   // <module>.Base.hello(hi:)
-  public var fullName: String {
+  public var fullName: String { // TODO: make description
     fatalError("NOT IMPLEMENTED YET: \(#function)")
   }
 }
@@ -412,7 +411,7 @@ public protocol DistributedTargetInvocationEncoder {
 //  ///
 //  /// Record the error type of the distributed method.
 //  /// This method will not be invoked if the target is not throwing.
-//  mutating func recordErrorType<E: Error>(_ type: E.Type) throws
+//  mutating func recordErrorType<E: Error>(_ type: E.Type) throws // TODO: make not adhoc
 
 //  /// Ad-hoc requirement
 //  ///