Add storefront-info-endpoint configuration

[jameswestman]

If this configuration option is present, this endpoint will be used to get information about each app when it is uploaded. It can be used to validate or modify appstream files and to set the token type of the commit.

Depends on #69.

[jameswestman]

This adds a dependency on libostree >=2021.5 for rewriting commits. This caused some issues with CI, so I had to change the jobs to use Ubuntu 22.04 rather than latest (which is currently 20.04).

[danielsilverstone-ct]

There are a lot of places where you added an Eq derive - was this needed for the ostree stuff? In this instance it won't add a huge amount to compile times / binary size; but in general it's not a great idea to blanket-add derives unless you need them. Obvs. if you need them then so-be-it, which is why I didn't highlight them in the main review comments.

Generally this looks good; though I pretend no ability to judge the ostree work.

[jameswestman]

As for the Eq derives, that was a clippy warning--of course, it might be wrong.

[danielsilverstone-ct]

As someone with minimal experience of ostree etc. the Rust itself looks nice now.

[ramcq]

Would @dbnicholson or @cgwalters be able to take a look at the ostree surgery parts of this? It's a Rust version of some utterly crazy stuff we have in Endless OS which I made for renaming Flatpaks locally, using an in-memory mtree to commit updated metadata/etc files which have the app ID changed.

[cgwalters]

Overall looks sane to me, just some completely optional suggestions/notes

[jameswestman]

Pushed some changes:

• Minor code style changes (NONE_CANCELLABLE instead of ::<Cancellable>, etc.)
• Fix unnecessary re-commits caused by re-serializing the appstream XML
• Update ostree crate to 0.15

[barthalion]

@jameswestman Mind regenerating Cargo.lock after a rebase?