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/MergeSquashLevel.kt

@@ -14,6 +14,22 @@ internal fun mergeSquashLevel(): Level = level(
     hints = listOf("Take a look at the `--squash` option of the merge command. Don't forget to commit the merge!"),
     commandSuggestions = listOf("git merge --squash long-feature-branch", "git commit -m \"Merge long feature\""),
     setup = { RepoState(initialized = true, files = listOf(GitFile("file1", tracked = true)), branches = mapOf("master" to 2, "long-feature-branch" to 4)) },
+    nativeSetup = {
+        resetFiles()
+        write("file1")
+        addCommit("First commit", "file1")
+        checkoutNew("long-feature-branch")
+        write("file3", "some feature\n")
+        addCommit("Developing new features", "file3")
+        append("file3", "getting awesomer\n")
+        addCommit("Takes", "file3")
+        append("file3", "and awesomer!\n")
+        addCommit("Time", "file3")
+        checkout("master")
+        write("file2")
+        addCommit("Second commit", "file2")
+        true
+    },
     validator = repoPredicate { repo -> "merge-squash" in repo.maintenanceActions && repo.commits.isNotEmpty() },
     testCases = listOf(
         levelTestCase("squash merge then commit", "git merge --squash long-feature-branch", "git commit -m \"Merge long feature\""),