Move native level setups into level files

- Delete NativeLevelFixtures.kt and make native repository setup an optional property of each Level.
- Move every existing native setup into its corresponding level file so setup, validation, and tests stay together.
- Add the missing Blame native setup with config.rb history and a Spider Man password commit.
- Add a native runtime regression that verifies `git blame config.rb` identifies Spider Man on the password line.
- Verify the full JVM test suite using the compiled host Git runtime.

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

@@ -14,6 +14,18 @@ internal fun rebaseLevel(): Level = level(
     hints = listOf("You want to research the `git rebase` command"),
     commandSuggestions = listOf("git checkout feature", "git rebase master"),
     setup = { RepoState(initialized = true, headBranch = "master", branches = mapOf("master" to 2, "feature" to 2)) },
+    nativeSetup = {
+        resetFiles()
+        write("README", "readme\n")
+        addCommit("init commit", "README")
+        checkoutNew("feature")
+        write("feature", "feature\n")
+        addCommit("add feature", "feature")
+        checkout("master")
+        append("README", "content\n")
+        addCommit("add content", "README")
+        true
+    },
     validator = repoPredicate { repo ->
         repo.headBranch == "feature" &&
             repo.commits.take(3).map { it.message } == listOf("add feature", "add content", "init commit")