Base image drinternet/rsync as first party code

[Burnett01]

This action has been around and maintained for many years with 3.500+ projects depending on it.
As per demand, it is time to streamline/merge the base image code into this action code base.

In the next major version, the base image dependency (drinternet/rsync) will be included as a first party code into this project. This allows for easier code review and Q/A conducted by action users.
This also means that the action will have zero dependencies (other than alpine itself of course).
Both licenses are compatible (MIT) which should ease the migration/merge path.

Since the maintainer of the base image has always been a collaborator of this action,
nothing will change except that regular alpine version updates are done here as well.

[Burnett01]

I was able to retain the original commits for the files of the base image (drinternet/rsync)
via git filter-repo and I pushed it to a tracking branch in this repo here: drinternet-rsync-merge.

Log:

Stevens-MacBook-Pro: $ git clone https://github.com/JoshPiper/rsync-docker.git
remote: Enumerating objects: 295, done.
remote: Counting objects: 100% (109/109), done.
remote: Compressing objects: 100% (68/68), done.
remote: Total 295 (delta 59), reused 79 (delta 39), pack-reused 186

Stevens-MacBook-Pro: $ git filter-repo --path agent-add --path agent-askpass --path agent-autostart 
--path agent-start --path agent-stop --path hosts-add --path hosts-clear 
--path README.md --path LICENSE --path Dockerfile

Parsed 105 commits
New history written in 0.20 seconds; now repacking/cleaning...
Repacking your repo and cleaning out old unneeded objects

The histories of that branch and the history of this repo are unrelated,
leading to either a merge or rebase.

I am leaning towards a rebase in order to retain the commits of the base image files.
A merge would lead to a loss of the commits of those files.

A rebase will most likely take part against the upcoming non-release/8.0.0 version (which is currently in sync with master/main).

Please let me know if you are fine with a rebase of the base image files against the upcoming 8.0.0 release.

I will keep you updated how the progress is going. So far I will have to rebase each commit concerning the README.md and Dockerfile manually.

[Burnett01]

Currently no new progress on this topic due to time constraints, but I am on it