Auto merge of #29923 - mrobinson:test-scripts, r=jdm

Combine all script tests into `test-scripts`

Remove:
    - tidy self test support from `./mach test`
    - `./mach test-idl`

Adds a `./mach test-scripts` command that is responsible for running all
Python script tests. Run this during the CI to catch regressions in
changes to scripts. The WebIDL tests are still *very* slow and there are
from Gecko, so only run them when "-a" is passed meaning all tests.

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---
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- [x] `./mach build -d` does not report any errors
- [x] `./mach test-tidy` does not report any errors
- [x] There are tests for these changes

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python/wpt/__init__.py

@@ -12,6 +12,8 @@ import sys
 
 import mozlog.commandline
 
+from . import test
+
 SCRIPT_PATH = os.path.abspath(os.path.dirname(__file__))
 SERVO_ROOT = os.path.abspath(os.path.join(SCRIPT_PATH, "..", ".."))
 WPT_PATH = os.path.join(SERVO_ROOT, "tests", "wpt")
@@ -62,3 +64,7 @@ def update_args_for_legacy_layout(kwargs: dict):
     kwargs["include_manifest"] = os.path.join(
         WPT_PATH, "include-legacy-layout.ini"
     )
+
+
+def run_tests():
+    return test.run_tests()