fix(FEV-1542): countdown shows 10 sec after reaching to 0 and after seeking

[lianbenjamin]

Description of the Changes

the issue:
countdown component shows 10 sec when it shouldn't. see below use-cases:

1. when the player is about to switch to the next media, countdown reaches to 0 and then shows 10 before it disappears.
2. when the countdown comp is rendered (seek to almost the end of the video so it will show for example 7 sec) and performing seeking to a position that the comp should not be rendered (seek to somewhere in the beginning of the video)- countdown shows 10 sec before it disappears.

solution:
add a validation to shouldRender() func -> check the value of timeToShow state.

CheckLists

• changes have been done against master branch, and PR does not conflict
• new unit / functional tests have been added (whenever applicable)
• test are passing in local environment
• Travis tests are passing (or test results are not worse than on master branch :))
• Docs have been updated