Add cargo alias to run clippy

[matthewhughes934]

The alias allows us to centralise the lints we allow/deny in a single location. Also add a workflow to run this across all packages in PRs.

• I did not use an LLM to create a change in this PR.
• I used an LLM to create a change in this PR, and I have explained below how it was used.

[ytmimi]

Might want to add a section to the contributing docs that explains how to run clippy before submitting PRs.

[matthewhughes934]

Might want to add a section to the contributing docs that explains how to run clippy before submitting PRs.

👍 done

[ytmimi]

Been thinking about this, and although I'm not thrilled about the duplication I think the fact that we can run cargo clippy and have it "just work" is ultimately better for developers so let's go with #7116.