Prepare i18n file for translation (English Version)

[christpet]

Put all hardcoded text into an i18n file, and link it in the appropriate places in the UI

• Extension (https://storybook.lmem.net/?path=/story/extension-account--about)
• Profiles app (sources page, contributor profile pages)

[christpet]

@newick @lutangar @JalilArfaoui Where do you think is the best place to start with this? Do we need an overarching localization library?

Linked issues:

• 797

• 793

• 794

Please let me know if I missed a step!