Multiselect for territory filtering

[Soxasora]

Description

Completes #795
Adds support for multiple territories in item gathering queries.
Introduces Multi Select, a new component that lets you choose between multiple entries. And paired with MultiSubSelect, it delivers a new personal feed experience.

To start, enter a territory and press the '+' button. Multi Select will appear with the territory you're on, already picked.

Screenshots

Early UI, proof of concept

Select with Add button

Select and MultiSubSelect

MultiSubSelect full overview

MultiSubSelect full overview with lots of selected territories

Additional Context

WIP

Checklist

Are your changes backwards compatible? Please answer below:
n/a

On a scale of 1-10 how well and how have you QA'd this change and any features it might affect? Please answer below:
n/a

For frontend changes: Tested on mobile, light and dark mode? Please answer below:
Yes

Did you introduce any new environment variables? If so, call them out explicitly here:
No

Progress

WIP:

• Multi Select component
  -- Clean Multi Select from repetitive handles
  -- Better styling of dropdown
  -- Make adjustments to make it usable and validated in a Form

• Select component
  -- Don't show 'home' when using MultiSelect
  -- Adjust placement of '+' button

• Mechanisms
  -- Better query.sub gathering and composing
  -- Adjust Sorts (recent, random, top) to support Multi Select and query.sub as array

Functioning:

• Multi Select component
• Multi-territory feed
• Queries accepts arrays of Sub