New user option: Always show floating New Post button

The issue: Currently on the desktop site, if you're scrolled down the sidebar reading your notifications and want to post a new status, you have to leave your position to scroll back up. This seems like an unneccessary restriction given that the mobile post button and the modal for it exist and these work perfectly fine on the desktop version when not hidden by pleroma-fe.

The code: What this does is add a new option called "Always show floating New Post button" in the Compose section of the General settings tab. When enabled, pleroma-fe will no longer hide the New Post button. To prevent overlap with the Shoutbox, when this option enabled the Shoutbox will be moved to the left side instead of the right using a class and some CSS.

Issues with this: None known, this isn't adding a new component or anything but merely letting users access a feature they already have but was previously only accessible in the mobile nav.

Changelog and contributors file updated as well, and tested with npm run dev as well as on my instance (screens are from my instance)

Screens:

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• 4639e30c - Fix config naming for consistency

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There have been issues on mobile where you go to reply to someone and the post reply box opens up but the New Post floating button is still there too obscuring things and easy to hit causing some very amusing chaos

See description, I clarified when I submitted this MR about why there's shoutbox code in it. It's not unrelated as these two elements normally use the same bottom-right corner at different times. This seemed the cleanest way to address it, by just switching the shoutbox side to the left only if this option is enabled.

For reference, both of the user option merge requests are fully compatible with each other.

"To prevent overlap with the Shoutbox, when this option enabled the Shoutbox will be moved to the left side instead of the right using a class and some CSS."

I wanna know what @shpuld thinks of this

added 9 commits

• 4639e30c...338134ac - 8 commits from branch pleroma:develop
• cab00959 - Merge branch 'develop' into 'showMobileNewPost'

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added 3 commits

• cab00959...19475ba3 - 2 commits from branch pleroma:develop
• 6125dc88 - Update for latest develop merges to CHANGELOG

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resolved all threads

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• 6125dc88...425919a0 - 12 commits from branch pleroma:develop
• 179af131 - Fix changelog merge conflict

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merged

mentioned in commit a8a82ad1