tests: Add sysctl ipv6 and extra CI steps

[lexnv]

Changes the binding in response to

• Binding to localhost inside a container fails because ::1 doesn't exist docker/for-linux#1374
  This is achieved via --sysctl net.ipv6.conf.all.disable_ipv6=0

CI steps that are running now:

• cargo fmt
• cargo machete for unused dependencies (has detected one)
• cargo check
• cargo doc (with extra checks)
• cargo clippy
• cargo test

While at it, I've also fixed cargo doc tests.

I've added reorder_imports (similar to Substrate) to group imports from the same crate.

At the time being, the clippy step is allowed to fail to not block this PR further and a proper fix should land with: #57.

Builds on #56

[dmitry-markin]

@lexnv Do you think we should keep both --sysctl IPv6 fix and binding to IPv4 addresses?

[lexnv]

I think we could keep the sysctl fix, I'll revert my binding changes, good point thanks!

[lexnv]

@dmitry-markin Let me know what you think of it, since I've change quite a few things.

CI steps that are running now:

• cargo fmt
• cargo machete for unused dependencies (has detected one)
• cargo check
• cargo doc (with extra checks)
• cargo clippy
• cargo test

While at it, I've also fixed cargo doc tests.

I've added reorder_imports (similar to Substrate) to group imports from the same crate.
Since these are quite opinionated, would love to get your input on them, we could otherwise revert the parts you think are unnecessary / too restrictive 🙏

At the moment, the clippy step is allowed to fail to not block this PR further and a proper fix should land with: #57.

[dmitry-markin]

I've added reorder_imports (similar to Substrate) to group imports from the same crate.
Since these are quite opinionated, would love to get your input on them, we could otherwise revert the parts you think are unnecessary / too restrictive 🙏

Makes sense to me. Overall, you changes seem to be a big improvement, thank you!

One thing I don't understand / don't know how to check are all that github CI actions like:

uses: "andymckay/cancel-action@271cfbfa11ca9222f7be99a47e8f929574549e0a"

Not sure, how do we select the audited/trusted ones? (But may be if they work that's all we need to know.)