jakttest: Generate diffs from different runs

[cg-jl]

This allows us to know if any regressions have ocurred or if any extra tests have been fixed by new changes.

[cg-jl]

Some screenshots:

[cg-jl]

Removed the sh wraps since this problem also happens on the main branch; therefore it wasn't introduced by this.

[BuggieBot]

Hello!

One or more of the commit messages in this PR do not match the Jakt code submission policy, please check the lint_commits CI job for more details on which commits were flagged and why. Please do not close this PR and open another, instead modify your commit message(s) with git commit --amend and force push those changes to update this PR.

[cg-jl]

Closing since the cleaner ninja-like output makes it much easier to visually parse what has changed