Add multilocation assets to ADD NEW TOKEN modal

[lolmcshizz]

Currently we have AssetHub as a source for adding new external assets to our UI - however, this only explores the assets pallet and not foreignAssets - we also need the latter in order to easily allow users to add:

• tokens from projects that don't have channels open with Hydration but do have their asset registered on AssetHub
• Snowbridge tokens

[jak-pan]

This will be more complicated. We will need to wait for next runtime upgrade to fully support this I think. The problem is that foreign assets might be other parachain assets and we don't support directly sending them from AH as of this moment.. Snowbridge assets are exception as they are routed through AH and we use it as the source of truth