Add spelling and grammar checks to linting

[Kevsy]

Problem description

CAMARA API and Test definitions require manual spelling and grammar checks. An automated check should save time for reviewers and ensure consistency.

Possible evolution

• Spellcheck. Utilise an existing Github Action, e.g. check-spelling action as part of the validation workflow.
• Grammar check. Investigate options (I can't find a Github Action that performs a grammar check against YAML content).

Alternative solution

Additional context

I have been testing the check-spelling action against my personal test fork of Simple Edge Discovery, and it picks up spelling errors* which it adds as a comment to the commit. 'CAMARA words' can be accepted in advance via a config file. It can also exclude files from spellcheck, supports regex etc.

*these were deliberately made for the test, and are not in the CAMARA release.