Refactor x/staking Validation and Delegation tests based on MsgCreateValidator.Pubkey type change. (#7526)

* testing: refactore Validation and Delegation handling of x/staking

This Changeset introduces set of improvements for writing tests.

The idea is to create a testing subpackage which will provide functions
to make tests more dev-friendly and wrap higher level use-cases.
Here is a show-up of of creating a service for staking module
for tests.

This PR also changes the `x/staking/types.MsgCreateValidator.Pubkey` from string
to types.Any. This change motivated the other change to show the pattern I'm describing here.

* add validator checks

* type change fixes

* use deprecated

* adding test slashing

* new network comment update

* working on tests

* Fix TestMsgPkDecode test

* Add UnpackInterfaces to MsgCreateValidator

* Fix tests

* Convert bech32 pubkey to proto

* Fix test

* fix v039/migrate_test/TestMigrate

* fix tests

* testslashing: rename Service to Helper

* file rename

* update TestMsgDecode

Co-authored-by: blushi <marie.gauthier63@gmail.com>
Co-authored-by: Amaury Martiny <amaury.martiny@protonmail.com>
Co-authored-by: Cory Levinson <cjlevinson@gmail.com>

x/auth/types/account.go

@@ -14,7 +14,6 @@ import (
 	"github.com/cosmos/cosmos-sdk/codec"
 	codectypes "github.com/cosmos/cosmos-sdk/codec/types"
 	sdk "github.com/cosmos/cosmos-sdk/types"
-	sdkerrors "github.com/cosmos/cosmos-sdk/types/errors"
 )
 
 var (
@@ -84,22 +83,11 @@ func (acc BaseAccount) GetPubKey() (pk crypto.PubKey) {
 
 // SetPubKey - Implements sdk.AccountI.
 func (acc *BaseAccount) SetPubKey(pubKey crypto.PubKey) error {
-	if pubKey == nil {
-		acc.PubKey = nil
-	} else {
-		protoMsg, ok := pubKey.(proto.Message)
-		if !ok {
-			return sdkerrors.ErrInvalidPubKey
-		}
-
-		any, err := codectypes.NewAnyWithValue(protoMsg)
-		if err != nil {
-			return err
-		}
-
-		acc.PubKey = any
+	any, err := codectypes.PackAny(pubKey)
+	if err != nil {
+		return err
 	}
-
+	acc.PubKey = any
 	return nil
 }