scripts: Add check-branches.py utility.
This script list the enabled worktrees and the branch of each subproject.
It's useful to keep track of the state of our working environment.
Output example:
$ scripts/check-branches.py
Worktrees:
/home/vjaquez/gst/gst-build 2b497bd [master]
/home/vjaquez/gst/gst-build-1.16 33e1ea6 (detached HEAD)
gst-build
## master...origin/master [ahead 1]
2b497bd scripts: Add check-branches.py utility.
orc
## HEAD (no branch)
gstreamer
## master...origin/master
gl-headers
## HEAD (no branch)
gst-plugins-base
## master...origin/master
gst-plugins-good
## master...origin/master
libnice
## master...origin/master
avtp
## HEAD (no branch)
dssim
## dssim1-c...origin/dssim1-c
libmicrodns
## HEAD (no branch)
openh264
## HEAD (no branch)
gst-plugins-bad
## master...origin/master
gst-plugins-ugly
## master...origin/master
FFmpeg
## meson-4.3.1...origin/meson-4.3.1
gst-libav
## master...origin/master
gst-rtsp-server
## master...origin/master
gst-devtools
## master...origin/master
gst-integration-testsuites
## HEAD (no branch)
gst-editing-services
## master...origin/master
gstreamer-vaapi
## master...origin/master
pycairo
## HEAD (no branch)
pygobject
## pygobject-3-38...origin/pygobject-3-38
gst-python
## master...origin/master
gst-examples
## master...origin/master
gst-docs
## master...origin/master
gst-instruments
## master...origin/master