Fixes a null pointer in TranscoderUtils when retrieving the duration value from a track by checking if the field is present before accessing it.
Updated logic of estimateVideoTrackBitrate API in TranscoderUtils to utilize the source media file duration in cases where track specific duration value is null.
Updated logic of createTargetMediaFormat API in MediaTransformer class to use a default bit rate of 10_000_000 when we fail to estimate a valid bitrate from the source media track.