Change the package base name of the Go code, from
`git.blender.org/flamenco` to `projects.blender.org/studio/flamenco`.
The old location, `git.blender.org`, has no longer been use since the
[migration to Gitea][1]. The new package names now reflect the actual
location where Flamenco is hosted.
[1]: https://code.blender.org/2023/02/new-blender-development-infrastructure/
Workers now send output produced by Blender (limited to PNG and JPEG
images, currently) to Manager. This is done by converting to JPEG first,
then sending the bytes via the Flamenco API to the Manager.
