Add support for the --hosting-base-path argument to docc_archive

[amorde]

Update docc_archive to support providing a value for the --hosting-base-path argument for docc convert.

From docc convert --help:

OVERVIEW: Converts documentation from a source bundle.

USAGE: docc convert [<options>] <source-bundle-path>

ARGUMENTS:
  <source-bundle-path>    Path to a documentation bundle directory.
        The '.docc' bundle docc will build.

OPTIONS:
   [extra output omitted]

  --hosting-base-path <hosting-base-path>
                          The base path your documentation website will be hosted at.
        For example, to deploy your site to 'example.com/my_name/my_project/documentation' instead of 'example.com/documentation', pass '/my_name/my_project' as the base path.
  -h, --help              Show help information.

[luispadron]

Thanks! Mind adding a test over here if possible: https://github.com/bazelbuild/rules_apple/blob/master/test/starlark_tests/docc_tests.bzl