Install previous versions of hb apps

[TomIndi]

Is your feature request related to a problem? Please describe.
I just accidentally updated mission control for a newer version of atmosphere then I am on and now I have to manually place the older version to my sd card.

Describe the solution you'd like
Id Really love for there to be an option to install previous versions of homebrew applications

Platform:
Switch and maybee Wii U

[vgmoose]

I like this idea a lot. We don't re-host any packages on our CDN except the most recent version, however.

That being said, it would be possible to pull/list out older versions of a package's pkgbuild.json through the github API. The client could do this, allowing the user to select an older version, and then hit Github directly to download and extract the older version (assuming the developer still has the upstream release URL present).

For a specific example of MissionControl, we can list out all the commits that affect its pkgbuild on Github like this: https://github.com/fortheusers/switch-hbas-repo/commits/main/packages/MissionControl/pkgbuild.json

And via the Github API:

List all commits for a given package's pkgbuild: https://api.github.com/repos/fortheusers/switch-hbas-repo/commits?path=packages/Checkpoint/pkgbuild.json&sha=main

Get base64 pkgbuild.json content for a given commit: https://api.github.com/repos/fortheusers/switch-hbas-repo/contents/packages/Checkpoint/pkgbuild.json?ref=0b4099ebd1808f34867995c7ddc5aedbfbe232b5

These two endpoints, combined with Chesto's new Dropdown component would make it pretty easy to rewind to an older package version.

But there is another obstacle which is, that would mean we need to parse these pkgbuild's extraction logic on the client. This would effectively mean reimplementing Spinarak (the python .zip file builder that parses these files) in C++. That's also desirable for other reasons, such as allowing users to grab latest releases directly from Github without having to rely on our rehosted versions. There are some tradeoffs (such as Github API limits) but for a simple one-off downgrade or nightly update, it would still be a useful feature.

So TLDR: it's doable, and we have the repo metadata now to allow rewinding to older apps, but it would need client changes to support it.