i18n syntax additions with nested HTML

[rebecca-shoptaw]

Subtask of #9486.

Fix. This PR adds i18n syntax in cases where the text to be translated includes HTML opening/closing tags. See the i18n guide for full syntax info and instructions.

Technical

Separated the PR's by i18n syntax type for ease of review, this one is scoped to cover all the HTML tag-including syntax, i.e. $:_('Please <a href="">click here</a> to learn more').

Also includes removing relevant files from i18n exclude list so as to confirm they now pass the detect-missing-i18n check.

Testing

1. Find a newly i18n-ed phrase in one of the files that includes nested HTML
2. Confirm that the syntax includes a :
3. Confirm that any included opening tags also have a corresponded included closing tag, i.e. $:_('Please <a href="">click here')</a> is incorrect
4. Check to see that the phrase appears correctly in the messages.pot file
5. Run the i18n detection script with pre-commit run detect-missing-i18n --all-files
6. No errors should appear, and the check should pass

Screenshot

Stakeholders

@mekarpeles @cdrini @pidgezero-one

[scottbarnes]

Thanks for this, @rebecca-shoptaw. Just one minor suggestion.

[rebecca-shoptaw]

@scottbarnes It looks like one of my last WARN fixes got lost in the rebase shuffle, $('Inventaire.io: ') in author/view.html should be switched to $_("Inventaire.io: ") since we made the call that we do want to translate brand names (and even if we didn't, we switched to the skip-line comment for exclusions instead of this syntax).

[scottbarnes]

@rebecca-shoptaw, that makes sense about Inventaire.io; I put that back.

For the issue with the i18n missing strings detection, I just ended up adding an exception to the script, and I am requesting a review from @cdrini.

Also, while reviewing this, I noticed some other files may be eligible for deletion, and they may deserve investigation in a separate issue.

It appears that openlibrary/templates/account/email/forgot.html can be deleted, on the theory it is not linked to anywhere, though I only gave this a cursory glance. If it can be deleted, we should decide about deleting the endpoint as well. It is still functional and the template still works.

Another candidate for deletion is openlibrary/admin/templates/admin/index.html, which appears to be an older version of openlibrary/templates/admin/index.html.

Because I made a substantive change to scripts/detect_missing_i18n.py (see 3b085b5), I am requesting a review from @cdrini, as mentioned above.

[rebecca-shoptaw]

@scottbarnes Sounds good, and thank you for digging into this!!

[cdrini]

Lgtm!

[cdrini]

Oh and something for a future PR: We can delete the python code for admin/loans too! class loans_admin