fix(ADA-111): Seek backwards’ and ‘Seek forward’ labels (#816)

issue:
in case props.step is null the label of seek button is "seek backwards/forwards" and not with specific time

solution:
use the default step in case of props.step is null

solves ADA-111

src/components/forward/forward.js

@@ -37,7 +37,7 @@ const mapStateToProps = state => ({
  * @returns {Object} - The object translations
  */
 const translates = (props: any) => ({
-  forwardText: !props.step ? <Text id={'controls.forward'}></Text> : <Text id={'controls.secondsForward'} fields={{seconds: props.step}}></Text>
+  forwardText: <Text id={'controls.secondsForward'} fields={{seconds: props.step || FORWARD_DEFAULT_STEP}}></Text>
 });
 /**
  * Forward component

src/components/rewind/rewind.js

@@ -37,7 +37,7 @@ const mapStateToProps = state => ({
  * @returns {Object} - The object translations
  */
 const translates = (props: any) => ({
-  rewindText: !props.step ? <Text id={'controls.rewind'}></Text> : <Text id={'controls.secondsRewind'} fields={{seconds: props.step}}></Text>
+  rewindText: <Text id={'controls.secondsRewind'} fields={{seconds: props.step || REWIND_DEFAULT_STEP}}></Text>
 });
 /**
  * Rewind component