libs/common: Refactor libs/common 4 (#4237)

* libs/common: Refactor libs/common 4

- move byte function out of cmn to its own pkg
- move tempfile out of cmn to its own pkg
- move throttletimer to its own pkg

ref #4147

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

* add changelog entry

* fix linting issues

types/genesis.go

@@ -10,6 +10,7 @@ import (
 	"github.com/pkg/errors"
 
 	"github.com/tendermint/tendermint/crypto"
+	tmbytes "github.com/tendermint/tendermint/libs/bytes"
 	cmn "github.com/tendermint/tendermint/libs/common"
 	tmtime "github.com/tendermint/tendermint/types/time"
 )
@@ -39,7 +40,7 @@ type GenesisDoc struct {
 	ChainID         string             `json:"chain_id"`
 	ConsensusParams *ConsensusParams   `json:"consensus_params,omitempty"`
 	Validators      []GenesisValidator `json:"validators,omitempty"`
-	AppHash         cmn.HexBytes       `json:"app_hash"`
+	AppHash         tmbytes.HexBytes   `json:"app_hash"`
 	AppState        json.RawMessage    `json:"app_state,omitempty"`
 }