Feature-gates in pattern matching of CosmWasm 2.0 Enum Variants

[AmitPr]

With the cosmwasm_2_0 default feature disabled, compilation of cw-multi-test fails with an error along the lines of the below:

error[E0599]: no variant or associated item named `Any` found for enum `CosmosMsg` in the current scope
   --> /cw-multi-test-2.0.1/src/app.rs:666:24
    |
666 |             CosmosMsg::Any(msg) => self
    |                        ^^^ variant or associated item not found in `CosmosMsg<_>`

error[E0599]: no variant or associated item named `Grpc` found for enum `QueryRequest` in the current scope
   --> /cw-multi-test-2.0.1/src/app.rs:694:27
    |
694 |             QueryRequest::Grpc(req) => self.stargate.query_grpc(api, storage, &querier, block, req),
    |                           ^^^^ variant or associated item not found in `QueryRequest<_>`

This PR feature gates these enums to allow compilation to succeed when the cosmwasm_2_0 feature is disabled.

[webmaster128]

We should have a CI job that would catch this (cargo build --no-default-features and cargo test --no-default-features). There are a few more to be cleaned up.