Re-evaluate checked-in generated sources

[jannic]

The generated sources in src/ cause a lot of noise in merge requests.

Evaluate if there is a better way. As @ithinuel wrote in the matrix room: "I'm starting to wonder if you shan't remove the src from the main branch and rather have a pipeline run and generate a parallel branch with the generated code ala gh-pages."

Disadvantages of a separate branch could be:

• Increased workflow complexity
• Repo layout less obvious, especially for casual observers and newcomers
• Reviewers can't easily see the effect of changes on the resulting crate

[AkiyukiOkayasu]

I agree that it is difficult to review, but it is easier for beginners to understand if the source is in the main branch.

I think it is the regression caused by svd2rust or svdtool updates that we should be worried about. I have not fully researched this yet, but what about including rp2040 in svd2rust-regress?

[ithinuel]

We could keep the branch with the generated sources as the visible branch but ask for contributions to be made on a dev branch.

This'd keep the best of both worlds for the cost of slightly increased complexity for contributors.