Add vDOT as foreign asset

[nud3l]

Is your feature request related to a problem? Please describe.
Vaults like LSTs as collateral. We only support LDOT on Interlay at the moment.

Describe the solution you'd like
Add Bifrost vDOT as foreign asset.

[sander2]

LDOT is already registered

[nud3l]

Thanks, adjusted the issue.

[sander2]

To quote Philipp:

The current blocker is the price sourcing though. vDOT is not available on coingecko and DIA is still working on implementing the price feed for vDOT.

Also, the UI depends on the coingecko field in the assetregistry, so we need that before we can register it. (or, we can register it without coingecko, but then we'd need another proposal later on to add it, so I'd say it's not worth registering now)