Update deps, Federation v2 prep

[jgautheron]

"Fall cleaning" 🍂

• Update GH action versions
• Update docker image versions
• Update Cargo deps, move deps up to workspace
• Clippy + sort grouping
• Upgrade to async-graphql 6
  • If extend schema @link detected, set the federation version (and do not send an error)
• Apply same Rust formatting rules as https://github.com/async-graphql/async-graphql

Fixes #7
Fixes #27

[jgautheron]

@sunli829 if you could have a look when you have a moment 🙏🏼

[humb1t]

@jgautheron thanks a lot for this huge update!
I forked grapgate, to maintain it because we use it in production and @sunli829 mentioned that original graphgate is no longer maintained.

I merged your branch into my fork https://gitlab.com/oss47/graphgate - if you are interested, we can use and maintain it together. You will find some minor changes there already and some going to come.

It's also available in docker registry: registry.gitlab.com/oss47/graphgate