fix(FEC-14300): gaps in the timeline progress

[lianbenjamin]

Description of the Changes

bugfix - regression.

the issue:
when loading a video with chapters, there are gaps in the progress of the timeline.

root cause:
since changes in CR-152- the timeline manager is not registered as a service anymore, so reset() is not being invoked when changing media. As a result, when switching media there are duplicated chapters (and timeline segments).

solution:
add reset() to timelineManagerAPI service.

Solves FEC-14300

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