* [Observation] Transition to peer macros instead of arbitrary members
* [Observation] Lift the initializer requirement by utilizing init accessors for fully formed definite initialization
* [Observation] Gate enabling of peer macros by flag
* [Observation] Enable feature for InitAccessors in the observation tests
* [Observation] Add tests to validate memberwise and definite initialization
* [Observation] Change visibility of observation runtime functions to be hidden
* [Observation] Update API requirements for Observable AsyncSequence names and alter the behavior of value emissions to be based upon transactionality
* [Observation] Slight naming alteration of isolation -> isolatedTo
Note: This re-enables the previously disabled tests since the implementation should be considerably more robust to hangs.
* Move `add_pure_swift_host_library()` from lib/CMakeLists.txt to
AddPureSwift.cmake so that code outside `lib` can use it
* Add `add_pure_swift_host_tool()` function to make a pure Swift
host executable target (for future usages)
* Specify depending `SwiftSyntax` modules explicitly because not all
Swift libraries uses all SwiftSyntax libraries
Refactor the build support for ASTGen and ObservationMacros. Both have
nearly-identical copies of a bunch of messy, workaround-laden CMake
code to build "pure" Swift host libraries using CMake's Swift support.
Instead, introduce `add_pure_swift_host_library` to centralize all of
the hacks to build a host library that's all Swift, using CMake's
support directly (rather than custom commands), and link against the
swift-syntax stack. Switch ASTGen directly over to this.
Add `add_swift_macro_library` on top of this, to make it easy to
create a macro library and install it into the appopriate plugin
directory. Switch ObservationMacros over to this.
