Snipets tooling update

- update README
- generate-md.py: ignore trailing newlines when complaining about diffs
- all langs: add more dependencies to templates
- all langs: support @hide-start and @hide-end for multi-line hiding
- go: also allow one-line imports
- java: allow declarations other than `main` method
- python, typescript: implement `unshorten` for implicit imports and
  client initialization
- python: add mypy config as `datasets` lacks type py.typed
- python: hide `# mypy:` annotations
- typescript: add tsconfig that allows top-level `await`s
- typescript: depend on @types/node to fix `import ... from "crypto"`

automation/snippets/generate-md.py

@@ -52,11 +52,11 @@ def main() -> None:
                     snippet_dir / f"{lang.NAME}.md",
                 )
                 handwritten = (snippet_dir / f"{lang.NAME}.md").read_text()
-                if handwritten != generated:
+                if handwritten.rstrip("\n") != generated.rstrip("\n"):
                     print_and_colorize_diff(
                         difflib.unified_diff(
-                            handwritten.splitlines(keepends=True),
-                            generated.splitlines(keepends=True),
+                            handwritten.rstrip("\n").splitlines(keepends=True),
+                            generated.rstrip("\n").splitlines(keepends=True),
                             fromfile=str(handwritten_fname),
                             tofile=str(generated_fname),
                         ),