Create `TaxonSelect` component for the new admin

[benjaminwil]

Desired Behavior

• A discrete TaxonSelect component that can be reused by application developers.
• It should use Spree::Taxon#pretty_name-like formatting to make it easy for admins to select the correct taxons from a list of all taxons.

(Optional) Current Behavior

The basic functionality exists in solidus_admin but it needs to be extracted to a component.

The basic functionality does not use #pretty_name-like values, making it more difficult to be sure the correct taxon has been selected.

(Optional) Additional notes

See more conversation about the current behaviour and its issues on #6610.