Adds a cli arg to `run_all_tests.py` for testing a selected extension (#753)

# Description

Add a cli argument `--extension` to run only unit tests for a selected
extension. As an example:

```bash
isaaclab -t --extension omni.isaac.lab_assets # Only runs tests under omni.isaac.lab_assets
```

Fixes #752 

## Type of change

- New feature (non-breaking change which adds functionality)

## Checklist

- [x] I have run the [`pre-commit` checks](https://pre-commit.com/) with
`./isaaclab.sh --format`
- [x] I have made corresponding changes to the documentation
- [x] My changes generate no new warnings
- [ ] I have added tests that prove my fix is effective or that my
feature works
- [ ] I have updated the changelog and the corresponding version in the
extension's `config/extension.toml` file
- [x] I have added my name to the `CONTRIBUTORS.md` or my name already
exists there

tools/run_all_tests.py

@@ -70,6 +70,7 @@ def parse_args() -> argparse.Namespace:
     parser.add_argument("--discover_only", action="store_true", help="Only discover and print tests, don't run them.")
     parser.add_argument("--quiet", action="store_true", help="Don't print to console, only log to file.")
     parser.add_argument("--timeout", type=int, default=DEFAULT_TIMEOUT, help="Timeout for each test in seconds.")
+    parser.add_argument("--extension", type=str, default=None, help="Run tests only for the given extension.")
     # parse arguments
     args = parser.parse_args()
     return args
@@ -83,6 +84,7 @@ def test_all(
     per_test_timeouts: dict[str, float] = {},
     discover_only: bool = False,
     quiet: bool = False,
+    extension: str | None = None,
 ) -> bool:
     """Run all tests under the given directory.
 
@@ -96,7 +98,8 @@ def test_all(
         discover_only: If True, only discover and print the tests without running them. Defaults to False.
         quiet: If False, print the output of the tests to the terminal console (in addition to the log file).
             Defaults to False.
-
+        extension: Run tests only for the given extension. Defaults to None, which means all extensions'
+            tests will be run.
     Returns:
         True if all un-skipped tests pass or `discover_only` is True. Otherwise, False.
 
@@ -126,6 +129,23 @@ def test_all(
                 break
         else:
             raise ValueError(f"Test to skip '{test_to_skip}' not found in tests.")
+
+    # Filter tests by extension
+    if extension is not None:
+        all_tests_in_selected_extension = []
+
+        for test_path in all_test_paths:
+            # Extract extension name from test path
+            extension_name = test_path[test_path.find("extensions") :].split("/")[1]
+
+            # Skip tests that are not in the selected extension
+            if extension_name != extension:
+                continue
+
+            all_tests_in_selected_extension.append(test_path)
+
+        all_test_paths = all_tests_in_selected_extension
+
     # Remove tests to skip from the list of tests to run
     if len(tests_to_skip) != 0:
         for test_path in all_test_paths:
@@ -303,6 +323,7 @@ if __name__ == "__main__":
         per_test_timeouts=PER_TEST_TIMEOUTS,
         discover_only=args.discover_only,
         quiet=args.quiet,
+        extension=args.extension,
     )
     # update exit status based on all tests passing or not
     if not test_success: