Import and regenerate with 1.19.1 gst-gir-files
As per !779 (comment 932998). This also:
- Bumps the CI to use 1.19.1 binaries;
- Adds
v1_20
features; - Minor fixes and changes that are only possible or needed for
v1_20
.
As per !779 (comment 932998). This also:
v1_20
features;v1_20
.