Refactor "toot" and "post" to reflect nouns and verbs

[vollkorntomate]

Summary

I refactored the usage of the string "toot" and "post" and split them into separate localization keys "toot.action" and "toot.noun" ("post.action"/"post.noun"), since it wasn't flexible enough to handle both the action of tooting/posting as well as the noun/object of a toot/post. This caused many translations to use the same word for both things, resulting in wrong grammar.

Since (of the existing translations) I only know German, English, French and Spanish, the other translations might be inaccurate and need fixing.

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[jzzocc]

Would you mind changing this to limit the scope to just changing the keys and submit updated strings at https://crowdin.com/project/metatext instead? I will get around to adding InfoPlist.strings there soon as well, thanks for bringing that to my attention

[vollkorntomate]

I updated the PR to only change the "toot" and "post" word usage, and fixed the translations for German in the Crowdin project, just like you suggested.