replace dep with go modules (#16017)

- guide shamelessly stolen from prometheus/prometheus
- updates local interface of oauth exchange
- updates local impl of hclogger
- bump jaeger client version

closes #16088

vendor/github.com/go-sql-driver/mysql/connection_go18.go

@@ -17,25 +17,22 @@ import (
 )
 
 // Ping implements driver.Pinger interface
-func (mc *mysqlConn) Ping(ctx context.Context) error {
+func (mc *mysqlConn) Ping(ctx context.Context) (err error) {
 	if mc.closed.IsSet() {
 		errLog.Print(ErrInvalidConn)
 		return driver.ErrBadConn
 	}
 
-	if err := mc.watchCancel(ctx); err != nil {
-		return err
+	if err = mc.watchCancel(ctx); err != nil {
+		return
 	}
 	defer mc.finish()
 
-	if err := mc.writeCommandPacket(comPing); err != nil {
-		return err
-	}
-	if _, err := mc.readResultOK(); err != nil {
-		return err
+	if err = mc.writeCommandPacket(comPing); err != nil {
+		return
 	}
 
-	return nil
+	return mc.readResultOK()
 }
 
 // BeginTx implements driver.ConnBeginTx interface
@@ -152,22 +149,21 @@ func (mc *mysqlConn) watchCancel(ctx context.Context) error {
 		mc.cleanup()
 		return nil
 	}
+	// When ctx is already cancelled, don't watch it.
+	if err := ctx.Err(); err != nil {
+		return err
+	}
+	// When ctx is not cancellable, don't watch it.
 	if ctx.Done() == nil {
 		return nil
 	}
-
-	mc.watching = true
-	select {
-	default:
-	case <-ctx.Done():
-		return ctx.Err()
-	}
+	// When watcher is not alive, can't watch it.
 	if mc.watcher == nil {
 		return nil
 	}
 
+	mc.watching = true
 	mc.watcher <- ctx
-
 	return nil
 }
 
@@ -200,3 +196,12 @@ func (mc *mysqlConn) CheckNamedValue(nv *driver.NamedValue) (err error) {
 	nv.Value, err = converter{}.ConvertValue(nv.Value)
 	return
 }
+
+// ResetSession implements driver.SessionResetter.
+// (From Go 1.10)
+func (mc *mysqlConn) ResetSession(ctx context.Context) error {
+	if mc.closed.IsSet() {
+		return driver.ErrBadConn
+	}
+	return nil
+}