Add transaction propagation for observed state mutations (#461)

* Add transaction propagation for observed state mutations

* Rename __animTx parameter to animTx and update provenance comments

* Add animation tests for @observable transaction propagation via direct and environment access

* Add animation tests for @observable withAnimation transaction propagation

* Make observable animation tests robust to Robolectric clock scheduling by asserting settle order

* Update skip-model dependency to 1.7.5 release instead of transaction-propagation branch

Author: marcprux

Package.swift

@@ -9,7 +9,7 @@ let package = Package(
     ],
     dependencies: [ 
         .package(url: "https://source.skip.tools/skip.git", from: "1.9.2"),
-        .package(url: "https://source.skip.tools/skip-model.git", from: "1.7.4"),
+        .package(url: "https://source.skip.tools/skip-model.git", from: "1.7.5"),
     ],
     targets: [
         .target(name: "SkipUI", dependencies: [.product(name: "SkipModel", package: "skip-model")], plugins: [.plugin(name: "skipstone", package: "skip")]),