fix(FEC-13857): search is cleared when prevent seek is enabled

[lianbenjamin]

the issue:
if searching for a text in transcript and new captions arrived, the search value is being cleared.
only reproduced when preventSeek feature is enabled.

root cause:
when preventSeek feature is enabled, the transcript is receiving new (current) captions from the cue-point service, which causing to re-render the transcript including the search bar.
current implementation is clearing the search value whenever the "old" captions are different from "new" captions, which only happened when captions language was switched - used to work with static data, rather than dynamic.

solution:

• add a new prop which states the active caption language
• clear the search value only if the active caption language has changed
• Also, trigger the search when new captions were added to the transcript for the same language (in order to have results also for the new captions)

Solves FEC-13857