feat: add PREPEND_LOCALE_PATHS configuration setting to Maple

[keithgg]

#Description

Backports the changes made in #29851 to maple.master.

edx-platform currently supports COMPREHENSIVE_THEME_LOCALE_PATHS setting, which appends paths to the end of LOCALE_PATHS, but there's currently no way to add additional paths to the start of the list to override the default translations.

In this PR, we added the PREPEND_LOCALE_PATHS setting to achieve this.

• Affects the Operator

Supporting information

• PR for the configuration repo. feat: add PREPEND_LOCALE_PATHS configuration setting openedx-unsupported/configuration#6677
• SE-5299

Testing instructions

On the docker devstack:

• make dev.shell.lms
• Edit the file /edx/etc/lms.yml. Add a PREPEND_LOCALE_PATHS setting like

PREPEND_LOCALE_PATHS: [/edx/src/]

• Copy a translation file into that folder.

cp -r /edx/app/edxapp/edx-platform/conf/locale/fr/ /edx/src/es

Note that this is copying French to Spanish folder. It makes seeing the differences easier.

• In your browser load the LMS, and change the openedx-language-cookie's value to es.
• Restart your lms dev server.
• If done correctly you should get the french translations loaded (it sometimes takes 5 minutes to load).

[openedx-webhooks]

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[pkulkark]

LGTM 👍

[keithgg]

@natabene can I get a review on this?

[natabene]

@keithgg Thank you for bringing this to my attention. Somehow this was missed.

[natabene]

@BbrSofiane Could you please line this up for your review? CC @jmbowman Just in case your team prefers to review.

[BbrSofiane]

@openedx-community-bot merge

[openedx-webhooks]

@keithgg 🎉 Your pull request was merged! Please take a moment to answer a two question survey so we can improve your experience in the future.