Remove crate_visibility_modifier feature

[jhpratt]

In some situations, pub(crate) wasn't strictly necessary, as it was
within a context where it would not be exposed regardless of scope. In
these situations, pub is used per request.

Pinging @SergioBenitez and @jebrosen for review. This should be looked through carefully to ensure nothing is inadvertently exposed or hidden. Checking the documentation should be sufficient for this.

[jebrosen]

I'll do a more thorough review against a diff, but generally LGTM.

[jhpratt]

For reproducing my check, you'll want to generate docs for the current master and this PR. Move the target/doc directories to some other (temporary) folder; I'll call these master and pr.

In both of these directories, run rm *.* and rm -r src. This will remove any artefacts that are unrelated to the diff and the file for source code — we know that one will change, we're only interested in the doc changes.

Next, run diff -r main pr > diff.txt. Open diff.txt up in a text editor. Since we're looking for the addition or deletion of functions, modules, constants, etc. the only lines relevant here are those with a difference in length. To quickly check this, I removed all irrelevant lines (---, 0c0, etc.), leaving just the file names and diff.

As of now, there are no lines with differing lengths, indicating that nothing was exposed or hidden accidentally.

[jebrosen]

Everything looks to be either crate -> pub(crate) or a crate -> pub that I have checked by hand to be contained in a non-pub path.

[jebrosen]

Test failures look unrelated -- UI test regression possibly from rust-lang/rust#64498.

[SergioBenitez]

@jebrosen That looks like a serious regression. I'm not sure if that's the PR to blame, but we should figure out what is.

[jebrosen]

you'll want to generate docs for the current master and this PR

You would actually need to do this with all features enabled in both debug and release mode. But that difference only applies to one or two types, and I also manually checked that everything is okay.

I'll merge once my local test run finishes.

[jebrosen]

Awesome! Merged as 4e6a7dd.