Support for cosmos-sdk v0.50, TM 0.38

[Anmol1696]

Overview

Pre-release out for cosmos-sdk version v0.50, it would be really helpful if we can start adding support for TM 0.38 which will be used.

[webmaster128]

In #1466 I tried using the Tendermint 0.37 client for Comet BFT 0.38. But this does not seem to work. We need a separate 0.38 client. Once we have that, we can easily adapt the auto-detection.

[Anmol1696]

Would it be similar to #1376?

[webmaster128]

What needs to be done is this:

1. Copy and commit the tendermint37 folder and Tendermint37Client into tendermint38 and Tendermint38Client. The diff should only be renamings here.
2. Test the new client against the 0.38 backend (set up in Create CometBFT 0.38 client and auto-detection #1466)
3. Make all changes required to make tests pass
4. Adapt the auto-selection in the higher level clients

[webmaster128]

In #1466 we have Comet 0.38 support done