Decide whether to import x/ibc from ibc-go and use it or update it.

[shiki-tak]

wasmd v0.27.0 uses v3 of ibc-go.
https://github.com/cosmos/ibc-go/blob/v3.0.0/modules/core/24-host/validate.go#L21

I added DefaultMaxPortCharacterLength becase the source related to ibc has not been update in our repository.

It is necessary to decide whether to import and use or update x/ibc before developing IBCs.

Originally posted by @shiki-tak in #570 (comment)

[zemyblue]

I think it's better to remove x/ibc module in this repo and import ibc-go.

[ulbqb]

I think it is difficult to import ibc-go. So I updated x/ibc simply.