Add on-chain pubkey checking for new validators

[D4ryl00]

Description

If a valoper is registered with an unsupported key type (e.g. secp256k1 instead of ed25519) and GovDOA members vote YES to add it as validator without manually checking the key type, then the node will crash with the following error :

Error on ApplyBlock. Did the application crash? Please restart tendermint       {"module": "consensus", "err": "Error in validator updates: validator {g1jAddress... gpubkey... 1} is using pubkey /tm.PubKeySecp256k1, which is unsupported for consensus"}

We should prevent the node from crashing for production, and add a security mechanism like on-chain pubkey checking.

[MikaelVallenet]

I'll look to add pubkey kind check ASAP for new validators