Enable i18n

[pavish]

This PR Enables switching languages

Tasks:

• Use system default for login page
• After logging in, use value stored for user
• Ensure both en and js get loaded in parallel
• Add docs for building po files in Wiki (added in GH workflow to create draft release with built static files #3489)
• Build .po files in Dockerfile
• Show language switcher dropdown in password change page and superuser creation page? (Out of scope for this PR)
• Test a production setup

UX considerations

• Within the app, the language switcher is present in the profile page and users page.
  • 
• When the user installs and runs Mathesar for the first time, the language is automatically chosen based on the locale of the browser.
• In the super admin creation page, there's no option to switch languages.
  • 
• In the login page, there's an option to switch languages.
  • 
• Once the user logs in and sets their preference, it is retained in a cookie and the login page will choose the language based on that cookie, but the option is still present.
• Do we need the option to switch languages in the login page?
• Do we need this option in the super user creation page?
• If yes to the above, should we hide that select menu until we visually style it? (It's currently the default select menu and the appearance varies based on the browser)

Checklist

• My pull request has a descriptive title (not a vague title like Update index.md).
• My pull request targets the develop branch of the repository
• My commit messages follow best practices.
• My code follows the established code style of the repository.
• I added tests for the changes I made (if applicable).
• I added or updated documentation (if applicable).
• I tried running the project locally and verified that there are no
  visible errors.

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[pavish]

@ghislaineguerin @kgodey I've assigned you to review this PR to take a call on the UX considerations mentioned above for the language switcher that is visible on the login page, which was added as part of this PR.

[seancolsen]

I tried this out and it looks like it works great. Code changes look straightforward.

私たちのアプリケーションが日本語で表示されるのは本当にエキサイティングです!

...It's really exciting to see our application in Japanese!

[kgodey]

@pavish I would just merge this as-is and make a separate GitHub issue for the UX concerns you've listed here, I agree that the experience could be improved but I don't think it's bad enough to block release / we can fix in the next release.

[pavish]

make a separate GitHub issue for the UX concerns you've listed here

Sounds good.