implement tvar & cleanup

[super-nabla]

Essentially, the key update involves a shift to a more comprehensive parsing strategy, moving beyond line-by-line tokenisation. I've aimed to make the code more modular and readable, which I hope will contribute to easier maintenance.

See also the internationalisation guidelines at Meta: https://meta.wikimedia.org/wiki/Meta:Internationalization_guidelines

[gopavasanth]

@super-nabla, please review the workflow and make some updates accordingly.. Thanks!

[super-nabla]

@gopavasanth ok, done. Thank you for reviewing. :)
I had to adjust a few of the existing tests slightly. For example, based on https://meta.wikimedia.org/wiki/Meta:Internationalization_guidelines inline icons should be wrapped in "tvar" and not tagged with "translate".

[[File:smiley.png|alt=🙂]]

I also added new test cases as required.

[gopavasanth]

LGTM, Thanks!