[Feature] Have some method to automatically backup stack files

[psfshr]

Summary

Have a way to automatically backup stack files on changes

Detailed description

This partially follows on from #109

It would be useful to have a feature where, on saving a stack, a copy of the previous versions of the compose, .env, and config are backed up to a separate location on Unraid.

This could be a simple copy and tar.gz of the files before saving. Optionally with a "keep last n backups" option to prune old copies.

Alternatives considered

Alternative currently is to manually copy out the contents of the compose, .env, and settings to separate files.

[mstrhakr]

There is a backup, did you miss that in the settings? Only thing that's missing from what you described is previous versions which are not retained, but there are as many backups as you want which would cover that gap.

[mstrhakr]

Oh and I guess the backup doesn't happen when you save a stack, it's scheduled like a normal backup.