Problem: Interchain accounts are not enabled in chain-main

[devashishdxt]

ibc-go v3.0.0 introduced interchain accounts which can be enabled on chain-main. https://github.com/cosmos/ibc-go/blob/main/docs/migrations/v2-to-v3.md#ics27

Development plan:

To enable interchain accounts in chain-main, we need following things:

• Create ICA auth module (Problem: Missing ICA auth module for enabling interchain accounts #730)
• Integrate ICA auth module, ICA controller keeper and ICA host keeper in app.go and write upgrade handler (Problem: Interchain accounts are not enabled in chain-main #732)
• Write integration tests for interchain accounts (Problem: Missing integration tests for interchain accounts #733)

For each of the above mentioned steps, a separate PR will be created so that it is easy for review the code in PR.