replace SubjectProvider with Expect but do not yet remove

we cannot yet remove it because we still have addAssertion on Expect
and if we remove it, would also have one on AssertionContainer. Two
different definitions which would not work together. This also means:
- deprecate addAssertion/addAssertionsCreatedBy/createAndAddAssertion
  in Expect, add append... to AssertionContainer

.github/workflows/build-ubuntu.yml

@@ -20,7 +20,7 @@ jobs:
       - name: build
         run: ./gradlew build
 
-      # TODO 0.17.0 or 0.18.0 re-activate scala API
+      # TODO 0.18.0 re-activate scala API
       #            -   name: composite build atrium-scala2
       #                run: ./gradlew build
       #                working-directory: misc/tools/atrium-scala2-test

.github/workflows/build-windows.yml

@@ -47,7 +47,7 @@ jobs:
         run: ATRIUM_ANDROID_JAR="$PWD/android-jar-cache/android.jar" ./gradlew checkDexer
         shell: bash
 
-      # TODO 0.17.0 or 0.18.0 re-activate scala API
+      # TODO 0.18.0 re-activate scala API
       #            -   name: composite build atrium-scala2
       #                run: ./gradlew build
       #                working-directory: misc\tools\atrium-scala2-test