remove cosmossdk.io/x/* dependence in the root go module

[tac0turtle]

While spinning out modules from the cosmos sdk go.mod we introduced module imports into the cosmos sdk. We need to remove these.

• Baseapp
• Client (marko)
• Server
• Testutils

[odeke-em]

Perhaps we should think about spinning out the Go module for "cosmossdk.io/testutil" because in the root go.mod, the reason why we need a bunch of those modules added to the top level is because testutil/network uses them, it doesn't have a go.mod file and can't use a replace directive and guess what? Almost every module imports "github.com/cosmos/cosmos-sdk/testuti/*" per this command

$ git grep 'github.com/cosmos/cosmos-sdk/testutil' | cut -d":" -f1 | xargs dirname | sort | uniq

and that currently returns unique 148 directories that import it

[tac0turtle]

i dont think we should move the entire thing but parts of it, we will handle this issue

[tac0turtle]

i think testutils is the only worry here. since baseapp client and server will be deleted this year

[tac0turtle]

closing this in favour of #20279