* Expose stardoc() output files as runfiles

There's currently a nuisance with the `stardoc()` rule that presents
itself in `rules_python`:

    $ git clone https://github.com/bazelbuild/rules_python.git
    $ cd rules_python
    $ git checkout d314e96aaab18f60df50400d61214f7c1d71b8e6
    $ bazel run //docs:update
    cp: cannot stat 'bazel-bin/docs/packaging.md_': No such file or directory
    cp: cannot stat 'bazel-bin/docs/pip.md_': No such file or directory
    cp: cannot stat 'bazel-bin/docs/pip_repository.md_': No such file or directory
    cp: cannot stat 'bazel-bin/docs/python.md_': No such file or directory

A sample of the targets involved look like so:

    $ bazel cquery --output=build //docs:update + //docs:packaging-docs
    INFO: Invocation ID: 5fd7a652-0b0d-4827-98f5-c345b38b2178
    INFO: Analyzed 2 targets (0 packages loaded, 0 targets configured).
    INFO: Found 2 targets...
    # /home/jenkins/repos/rules_python/docs/BUILD:153:10
    sh_binary(
      name = "update",
      target_compatible_with = [],
      data = ["//docs:packaging-docs", "//docs:pip-docs", "//docs:pip-repository", "//docs:core-docs"],
      srcs = ["//docs:update.sh"],
    )
    # Rule update instantiated at (most recent call last):
    #   /home/jenkins/repos/rules_python/docs/BUILD:153:10 in <toplevel>

    # /home/jenkins/repos/rules_python/docs/BUILD:121:8
    stardoc(
      name = "packaging-docs",
      target_compatible_with = [],
      input = "//python:packaging.bzl",
      deps = ["//docs:packaging_bzl"],
      out = "//docs:packaging.md_",
    )
    # Rule packaging-docs instantiated at (most recent call last):
    #   /home/jenkins/repos/rules_python/docs/BUILD:121:8 in <toplevel>
    # Rule stardoc defined at (most recent call last):
    #   /bazel-cache/phil/bazel/_bazel_phil/adc54b5b09500e464f8a73095f3bd8e3/external/io_bazel_stardoc/stardoc/stardoc.bzl:110:15 in <toplevel>

The `update` target could instead reference the `*.md_` files directly
instead of referencing the `stardoc()` targets. But it's not obvious
that this is the desired work flow. It feels like users should be able
to depend on the `stardoc()` target instead of its predeclared output.

This patch fixes this by adding the predeclared outputs to the
target's runfiles. That lets the `rules_python` doc update target work
again.

    $ bazel run //docs:update
    'bazel-bin/docs/packaging.md_' -> 'docs/packaging.md'
    'bazel-bin/docs/pip.md_' -> 'docs/pip.md'
    'bazel-bin/docs/pip_repository.md_' -> 'docs/pip_repository.md'
    'bazel-bin/docs/python.md_' -> 'docs/python.md'

Resolves config_setting visibility failures from bazelbuild/bazel#12933:

```
ERROR: /var/lib/buildkite-agent/builds/bk-docker-zr2k/bazel-downstream-projects/stardoc/distro/BUILD:33:8: in pkg_tar_impl rule //distro:distro_bins: target '@rules_pkg//pkg/private:private_stamp_detect' is not visible from target '//distro:distro_bins'. Check the visibility declaration of the former target if you think the dependency is legitimate
```

See https://buildkite.com/bazel/bazelisk-plus-incompatible-flags/builds/1320#018435e1-7429-4329-808a-731599f24623.

Needed for bureaucratic compliance reasons.

Input .bzl files are turned into runfiles of a custom Stardoc binary, which allows reusing the Java runfiles library to load the files while taking repository mappings into account.

Required updating the pinned Bazel commit and importing a patch to rules_jvm_external from the Bazel source tree.

Fixes #110

Needed for a bzlmod-compatible release