Investigate how to remove baseapp from module tests.

[julienrbrt]

After v2, baseapp & co won't be needed and those legacy part are being deleted from main.
However, to complete the baseapp removal, we need to remove the usage of baseapp from modules (x/) tests.

Proposal

From v0.52 and v2 modules should only use cosmossdk.io/core and we've created a minimal dependency cosmossdk.io/core/testing package for testing.

We should extend cosmossdk.io/core/testing with mock services and possibly more, in order to replace all baseapp and sdk.Context usage in module tests.

Requirements

It is very important to NOT import server/v2 packages (including stf and appmanager) and runtime/v2 packages in modules.
When the whole system needs to be tested, the integration/v2, simulations and systemtests frameworks can be used.
This should only be focusing in unit testing, which is why only core/testing should be required.

Note: it is possible that a test under x/ is more of an integration test than an unit test. If it is the case, move it and rewrite it accordingly.

Work breakdown

Once the framework is ready (+1 PoC module), migrate one module per PR.

• x/accounts
• x/auth
• x/authz
• x/bank
• x/circuit
• x/consensus
• x/distribution
• x/evidence
• x/feegrant
• x/gov
• x/group
• x/mint
• x/nft
• x/params
• x/protocolpool
• x/slashing
• x/staking
• x/tx
• x/upgrade
• x/epochs