grpc: Refactor grpc server test setup to pass in test context

[bharath-123]

Currently in the tests for the grpc server we have the method shared.SetupSharedService to setup the test environment. This method just takes in the number of blocks to initiate the test chain with.
We could expand this to take in arguments to have more configurable test setup.

We could define a struct like

type struct TestContext {
    bridgeAddresses map[uint32]*params.AstriaBridgeConfigs
    auctioneerAddresses map[uint32]string
   ......
}