gstcaps: add gst_caps_set_features_simple()

Convenient helper setting a caps feature on all the structures of a
caps.
6 jobs for caps-all in 29 minutes and 26 seconds (queued for 2 seconds)
Status Job ID Name Coverage
  Preparation
passed #61036
gst indent

00:00:31

passed #61035
manifest

00:00:32

 
  Build
passed #61037
build fedora x86_64

00:02:53

 
  Test
passed #61038
check fedora

00:14:55

 
  Full Builds
passed #61039
build android arm64 api28

00:05:27

passed #61040
build cerbero fedora x86_64

00:11:05