Add support for macro expansion in rustdoc source code pages

[GuillaumeGomez]

This is what it looks like:

You can test it here. In this case, I also enabled the --generate-link-to-definition to show that both options work well together.

Note: There is a bug currently in firefox where the line numbers are not displayed correctly if they're inside the "macro expansion" span. I didn't open a bug report yet, I plan to do so when I have a bit of time.

r? @notriddle

[rustbot]

Some changes occurred in HTML/CSS/JS.

cc @GuillaumeGomez, @jsha

These commits modify the Cargo.lock file. Unintentional changes to Cargo.lock can be introduced when switching branches and rebasing PRs.

If this was unintentional then you should revert the changes before this PR is merged.
Otherwise, you can ignore this comment.

[notriddle]

Why is this done differently than the normal expand/collapse system, but in code and in presentation?

[GuillaumeGomez]

Because it would force to duplicate all the common code. For example in:

func(arg, macro!(blabla), arg3);

Only macro!(blabla) will be different, so it's not interesting to duplicate all the rest. Instead, we put the original code in a span, the expanded one in another and then we can simply switch them based on the status of the checked property of the input. I'm also not a big fan of our current details approach as it requires more JS to be working fully as expected but it's a debate for another time.

[rustbot]

This PR modifies tests/run-make/. If this PR is trying to port a Makefile
run-make test to use rmake.rs, please update the
run-make port tracking issue
so we can track our progress. You can either modify the tracking issue
directly, or you can comment on the tracking issue and link this PR.

cc @jieyouxu

[GuillaumeGomez]

I opened the firefox bug report: https://bugzilla.mozilla.org/show_bug.cgi?id=1949948

[bors]

☔ The latest upstream changes (presumably #137511) made this pull request unmergeable. Please resolve the merge conflicts.

[GuillaumeGomez]

PR is ready for review.