feat: add tag selector custom setting component for `buildSettingComponent`

[davwheat]

Changes proposed in this pull request:

Creates a new TagSelector component, designed for use within buildSettingComponent in conjuction with core PR #3494.

This allows extensions to more easily select tag model instances within their settings pages.

Reviewers should focus on:

Checks may fail until #3494 is merged.

Screenshot

https://user-images.githubusercontent.com/7406822/174515268-493ee6e2-19ee-4a27-a7a6-7ce54ab8b4cb.mp4

Necessity

• [x] Has the problem that is being solved here been clearly explained?
• [x] If applicable, have various options for solving this problem been considered?
• [x] For core PRs, does this need to be in core, or could it be in an extension?
• [x] Are we willing to maintain this for years / potentially forever?

Confirmed

• [x] Frontend changes: tested on a local Flarum installation.
• [x] Core developer confirmed locally this works as intended.
• [x] Tests have been added, or are not appropriate here.

Required changes:

• [x] Related core PR: #3494
• [ ] Related core PR: #3456

[davwheat]

Moving Prettier to another PR

[luceos]

I like the idea of such a component very much. But I'm afraid that the design is too different from what we've used before. There's only a limited number of tags visible in the dropdown, they're structured differently and there might be quite a lot to scroll through. I'd prefer to see the frontend component re-used so that it would accept parameters and can be used in the admin and extensions.

Other maintainers please advice.

[SychO9]

I love the idea, though I agree with Daniël, I think we can reuse the TagSelectorModal component, although there might be some significant work needed to make it usable in a different context than what it was built for, but that would be perfect IMHO.

[davwheat]

The main issue I had is the fact that it's within a modal. This significantly limits use cases as noone else would be able to use the component within a modal due to current one-modal limitations in core.

We can definitely explore alternate designs -- maybe something like a textbox with autocomplete to more closely mirror the forum modal?

[SychO9]

Good point, maybe we can consider it after https://github.com/flarum/framework/pull/3456? it would be great if we can avoid reinventing the wheel.

[SychO9]

Superseded by https://github.com/flarum/framework/pull/3686