libs/common: refactor libs/common 2 (#4231)

* libs/common: refactor libs/common 2

- move random function to there own pkg

Signed-off-by: Marko Baricevic <marbar3778@yahoo.com>

* change imports and usage throughout repo

* fix goimports

* add changelog entry

privval/signer_client_test.go

@@ -8,7 +8,7 @@ import (
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 
-	"github.com/tendermint/tendermint/libs/common"
+	"github.com/tendermint/tendermint/libs/rand"
 	"github.com/tendermint/tendermint/types"
 )
 
@@ -24,7 +24,7 @@ func getSignerTestCases(t *testing.T) []signerTestCase {
 
 	// Get test cases for each possible dialer (DialTCP / DialUnix / etc)
 	for _, dtc := range getDialerTestCases(t) {
-		chainID := common.RandStr(12)
+		chainID := rand.RandStr(12)
 		mockPV := types.NewMockPV()
 
 		// get a pair of signer listener, signer dialer endpoints

privval/signer_listener_endpoint_test.go

@@ -11,6 +11,7 @@ import (
 	"github.com/tendermint/tendermint/crypto/ed25519"
 	cmn "github.com/tendermint/tendermint/libs/common"
 	"github.com/tendermint/tendermint/libs/log"
+	"github.com/tendermint/tendermint/libs/rand"
 	"github.com/tendermint/tendermint/types"
 )
 
@@ -66,7 +67,7 @@ func TestSignerRemoteRetryTCPOnly(t *testing.T) {
 	SignerDialerEndpointTimeoutReadWrite(time.Millisecond)(dialerEndpoint)
 	SignerDialerEndpointConnRetries(retries)(dialerEndpoint)
 
-	chainID := cmn.RandStr(12)
+	chainID := rand.RandStr(12)
 	mockPV := types.NewMockPV()
 	signerServer := NewSignerServer(dialerEndpoint, chainID, mockPV)
 
@@ -86,7 +87,7 @@ func TestRetryConnToRemoteSigner(t *testing.T) {
 	for _, tc := range getDialerTestCases(t) {
 		var (
 			logger           = log.TestingLogger()
-			chainID          = cmn.RandStr(12)
+			chainID          = rand.RandStr(12)
 			mockPV           = types.NewMockPV()
 			endpointIsOpenCh = make(chan struct{})
 			thisConnTimeout  = testTimeoutReadWrite