[Code Health] Ensure tokenomics module msg responses are non-empty (#975

)

## Summary

Ensure all supplier module msg responses are non-empty. This adds a
`Params` field to the following protobuf type(s), and updates the unit
tests to assert for presence and correctness.

- `MsgUpdateParamsResponse`

## Issue

- #663

## Type of change

Select one or more from the following:

- [ ] New feature, functionality or library
- [ ] Consensus breaking; add the `consensus-breaking` label if so. See
#791 for details
- [ ] Bug fix
- [x] Code health or cleanup
- [ ] Documentation
- [ ] Other (specify)

## Testing

- [ ] **Documentation**: `make docusaurus_start`; only needed if you
make doc changes
- [ ] **Unit Tests**: `make go_develop_and_test`
- [ ] **LocalNet E2E Tests**: `make test_e2e`
- [ ] **DevNet E2E Tests**: Add the `devnet-test-e2e` label to the PR.

## Sanity Checklist

- [x] I have tested my changes using the available tooling
- [ ] I have commented my code
- [x] I have performed a self-review of my own code; both comments &
source code
- [ ] I create and reference any new tickets, if applicable
- [ ] I have left TODOs throughout the codebase, if applicable

proto/poktroll/tokenomics/tx.proto

@@ -40,7 +40,9 @@ message MsgUpdateParams {
 
 // MsgUpdateParamsResponse defines the response structure for executing a
 // MsgUpdateParams message.
-message MsgUpdateParamsResponse {}
+message MsgUpdateParamsResponse {
+  Params params = 1;
+}
 
 // MsgUpdateParam is the Msg/UpdateParam request type to update a single param.
 message MsgUpdateParam {

x/tokenomics/keeper/msg_update_params.go

@@ -38,5 +38,7 @@ func (k msgServer) UpdateParams(ctx context.Context, msg *types.MsgUpdateParams)
 
 	logger.Info("Done updating params")
 
-	return &types.MsgUpdateParamsResponse{}, nil
+	return &types.MsgUpdateParamsResponse{
+		Params: &msg.Params,
+	}, nil
 }

x/tokenomics/keeper/msg_update_params_test.go

@@ -120,11 +120,12 @@ func TestMsgUpdateParams(t *testing.T) {
 
 	for _, test := range tests {
 		t.Run(test.desc, func(t *testing.T) {
-			_, err := srv.UpdateParams(ctx, test.req)
+			updateRes, err := srv.UpdateParams(ctx, test.req)
 			if test.shouldError {
 				require.Error(t, err)
 				require.ErrorContains(t, err, test.expectedErrMsg)
 			} else {
+				require.Equal(t, &test.req.Params, updateRes.GetParams())
 				require.Nil(t, err)
 			}
 		})