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/CheckoutFileLevel.kt

@@ -14,6 +14,13 @@ internal fun checkoutFileLevel(): Level = level(
     hints = listOf("You will need to do some research on the checkout command for this one."),
     commandSuggestions = listOf("git checkout -- config.rb"),
     setup = { RepoState(initialized = true, files = listOf(GitFile("config.rb", "This is the initial config file\nThese are changes you don't want to keep!", tracked = true)), commits = listOf(CommitNode("0000001", "Added initial config file")), branches = mapOf("master" to 1)) },
+    nativeSetup = {
+        resetFiles()
+        write("config.rb", "This is the initial config file")
+        addCommit("Added initial config file", "config.rb")
+        append("config.rb", "\nThese are changes you don't want to keep!")
+        true
+    },
     validator = repoPredicate { repo -> repo.files.find { it.name == "config.rb" }?.content == "This is the initial config file" },
     testCases = listOf(
         levelTestCase("checkout file from head", "git checkout -- config.rb"),