qtdemux: Put framerate into the closedcaption caps if it can be calculated from the stream

Using the same calculation used for video streams.
4 jobs for mov-cc-timescale in 10 minutes and 14 seconds (queued for 3 seconds)
Status Job ID Name Coverage
  Preparation
passed #57884
gst indent

00:00:31

passed #57883
manifest

00:00:22

 
  Build
passed #57885
build fedora x86_64

00:04:38

 
  Full Builds
passed #57886
build android arm64 api28

00:04:41