Add localization keys for all texts

[mrjvs]

Changes:

• Add localization keys for all texts
• Give <T /> a little upgrade to pass in components and values. For anything more complicated, the <Trans /> component should be used directly.
• Set up a convention to do KEY_NAME:VARIANT if there are multiple very similar variants of the same key

Special notes:

• Placeholder text for new posts is now the same on all platforms
• I wasn't sure if I should do meta tags, since they aren't shown to users and scrapers can't choose languages. So I chose not to translate them
• Reworded N/A to Unknown for unknown game_experience values
• I wasn't sure about moderator pages. Cuz then community will potentially translate stuff that is basically useless
• Backend driven data (like notifications) are still untranslated, it will need a rework of how those systems work.

Todos:

• Test if everything still looks correct
• Localize report pages