Invalid validator pubKey halts state machine

[hendrikhofstadt]

Summary of Bug

In Tendermint v0.27.0 only pubKeyTypes specified in ConsensusParams are allowed.

We can however still create validators with invalid key types which halts the chain since applyblock fails.

This is causing all of the integration tests to fail at the moment. Fixed in #2943 (tests only)

The handler for MsgCreateValidator needs to check whether the key is of a valid type.

Steps to Reproduce

• Create validator with invalid key type e.g. secp256k1

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[alexanderbez]

wow! Great catch @SLAMPER!