Change post visibility

[jazcarate]

Closes #64

Again with my awful UI 😅
I tried aligning the buttons to the right, like the UX when creating. Cound't CSS 🙈.
I tried the UX of having a ButtonDropdown but felt... off. Cant really explain.

Test are missing. I know. I started with #79 but got a bit derailed with #64 😳

Change you own post

A protected post

Seeing another user's post

Discussion point

It is weird that the links to the posts depend on the visibility. Now that we can change it, links will break.
Say I send you a link to http://drift/post/**protected**/91b769ab-b96e-4222-8501-95b0749a920e or http://drift.com/post/**private**/91b769ab-b96e-4222-8501-95b0749a920e, but then make it public; the old link will break.
I think any visibility should check the post ID and redirect accordingly to the current visibility.

[MaxLeiter]

I'll comment on some ideas for an improved UX when I think on it some more, but as a response to It is weird that the links to the posts depend on the visibility.: I agree, and it's actually not necessary anymore. I did that as public and unlisted posts can be SSG, which I removed to simplify the Docker setup, so now there's no real reason they can't all be /post/:id

[MaxLeiter]

@jazcarate I've removed the /protected and /private post sub-URLs. All posts are now under the /post/:id scheme.

67e1b98

[jazcarate]

I removed the margin of that button group (see image)
I added a delay loading
Made the visibility prop change; rather than the router recalculate
Made buttons be disabled, rather than appear and disappear when you change visibility

[MaxLeiter]

Looks great! Can you move the ButtonGroup to the right-side, similar to when creating a post?

I think this will eventually be moved to a proper edit page once I figure out post revisions, but it's great to have the functionality now.

[jazcarate]

Done :)