Remove pre-GRPC querier

[jkilpatr]

https://github.com/althea-net/cosmos-gravity-bridge/blob/main/module/x/gravity/keeper/querier.go

Is an unused file, this file used to back ABCI requests (the old query method for cosmos)

Now days it's mostly unused, except for one small but essential piece of code the contract deployer uses the 'QueryCurrentValset' endpoint. All of the others are totally unused.

PeggyJV has invested a non-trivial amount of time into adding GRPC support to the contract deployer and get around this issue.

As part of this issue

• evaluate if it's worth importing grpc support for contract deployer
• Use Github authoring features to ensure the original authors are credited if anything is imported.
• Delete all methods except QueryCurrentValset, or the entire querier.go file
• Transition all unit tests in queryier_test.go to test the grpc implementations.