ValidatorInfo rpc should return all validators, not just active and inactive ones

[Valentine1898]

Is your feature request related to a problem? Please describe.

ValidatorInfo rpc returns data only for active and inactive validators. This means clients cannot discover its existence if a validator is jailed or tombstoned.
This is especially critical for prax, which during modern epoch sync must retrieve all validators and store them in indexed-db to be able to display the user's stakes

By syncing only the modern block, we may lose some validators and stakes.
Example:
Epoch 2: the validator has joined the network
Epoch 3: user delegates tokens to validator
Epoch 4: validator jailed

If the user syncs from the beginning after epoch 5 and the validator remains jailed, we will never know about the existence of this validator and will lose the user stake

Also, it's an issue for other clients too. I think that for example, https://penumbra.today will not be able to display jailed validators

Describe the solution you'd like
ValidatorInfo rpc should return data of all validators regardless of their status

Additional context
related to penumbra-zone/web#1453