Add localization features

[char-lock]

Description

Implements use of localization files for strings in XKit Rewritten and sets the default locale to generic English. This allows for future translation and localization efforts to allow for multilingual usage of the extension.

• Created utility functions to pull localization information regardless of the browser.
• Added localization support for every string in the extension popup.
• Added localization support for individual script descriptions.

Testing steps

In general, the behaviour should be largely unchanged from the original extension, save the new ability to add localization profiles. If the user locale is English, everything will look and act the same as it did previously.