Fix Git editor reword workflow and UI coverage

- show Git editor file paths instead of the submitted git command
- surface follow-up commit message editors during interactive rebase reword
- add rename-commit UI tests for editor and amend-message solution paths
- add broader embedded level solution scenarios for alternate Git workflows

app/src/main/java/solutions/tretter/githugandroid/levels/MergeLevel.kt

@@ -30,6 +30,7 @@ internal fun mergeLevel(): Level = level(
     },
     testCases = listOf(
         levelTestCase("merge feature", "git merge feature"),
+        levelTestCase("merge feature with explicit merge commit", "git merge --no-ff feature -m \"Merge feature\""),
     ),
     negativeTestCases = listOf(
         levelTestCase("switching to feature does not solve", "git switch feature"),