Add a pofile syntax checker (#18270)
Closes #18269
Summary of the issue:
On the old translation system, pofile's syntax was checked before merging to NVDA.
The new system doesn't have this, leading to issues like #18252
Description of user facing changes:
Translators will receive warnings / errors with NVDA.po when uploading and downloading translations
Description of developer facing changes:
Add a pre-commit hook which checks the syntax of pofiles.
This will protect commits when pulling translations from crowdin.
