fix(bzlmod): correctly template repository macros for requirements, etc (#1190)

It seems that the macros for specifying the requirements break when the
user starts using `incompatible_generate_aliases=True`. This PR fixes
this.

Testing done:
1. Modify the example:
   ```
   $ git diff
diff --git a/examples/bzlmod/MODULE.bazel b/examples/bzlmod/MODULE.bazel
   index ce91228..1750210 100644
   --- a/examples/bzlmod/MODULE.bazel
   +++ b/examples/bzlmod/MODULE.bazel
   @@ -26,6 +26,7 @@ register_toolchains(
    pip = use_extension("@rules_python//python:extensions.bzl", "pip")
    pip.parse(
        name = "pip",
   +    incompatible_generate_aliases=True,
        requirements_lock = "//:requirements_lock.txt",
        requirements_windows = "//:requirements_windows.txt",
    )
   ```
2. Run `bazel build ...` and check that it is still working.

I noticed this when working on #1189 and creating a separate PR for
easier cherry-picking if we wanted to make a patch release which
includes this. I am not sure how I could make an automated test for this
other than creating a separate example.

python/pip_install/pip_repository.bzl

diff --git a/python/pip_install/pip_repository.bzl b/python/pip_install/pip_repository.bzl
index fce0dcd..1ea7bca 100644
--- a/python/pip_install/pip_repository.bzl
+++ b/python/pip_install/pip_repository.bzl
@@ -367,6 +367,15 @@
     else:
         build_contents += _bzlmod_pkg_aliases(repo_name, bzl_packages)
 
+    # NOTE: we are using the canonical name with the double '@' in order to
+    # always uniquely identify a repository, as the labels are being passed as
+    # a string and the resolution of the label happens at the call-site of the
+    # `requirement`, et al. macros.
+    if rctx.attr.incompatible_generate_aliases:
+        macro_tmpl = "@@{name}//{{}}:{{}}".format(name = rctx.attr.name)
+    else:
+        macro_tmpl = "@@{name}//:{{}}_{{}}".format(name = rctx.attr.name)
+
     rctx.file("BUILD.bazel", build_contents)
     rctx.template("requirements.bzl", rctx.attr._template, substitutions = {
         "%%ALL_REQUIREMENTS%%": _format_repr_list([
@@ -377,7 +386,7 @@
             "@{}//{}:whl".format(repo_name, p) if rctx.attr.incompatible_generate_aliases else "@{}_{}//:whl".format(rctx.attr.name, p)
             for p in bzl_packages
         ]),
-        "%%NAME%%": rctx.attr.name,
+        "%%MACRO_TMPL%%": macro_tmpl,
         "%%REQUIREMENTS_LOCK%%": str(requirements_txt),
     })
 

python/pip_install/pip_repository_requirements_bzlmod.bzl.tmpl

diff --git a/python/pip_install/pip_repository_requirements_bzlmod.bzl.tmpl b/python/pip_install/pip_repository_requirements_bzlmod.bzl.tmpl
index 462829d..1b2e217 100644
--- a/python/pip_install/pip_repository_requirements_bzlmod.bzl.tmpl
+++ b/python/pip_install/pip_repository_requirements_bzlmod.bzl.tmpl
@@ -12,13 +12,13 @@
     return name.replace("-", "_").replace(".", "_").lower()
 
 def requirement(name):
-    return "@@%%NAME%%//:" + _clean_name(name) + "_pkg"
+    return "%%MACRO_TMPL%%".format(_clean_name(name), "pkg")
 
 def whl_requirement(name):
-    return "@@%%NAME%%//:" + _clean_name(name) + "_whl"
+    return "%%MACRO_TMPL%%".format(_clean_name(name), "whl")
 
 def data_requirement(name):
-    return "@@%%NAME%%//:" + _clean_name(name) + "_data"
+    return "%%MACRO_TMPL%%".format(_clean_name(name), "data")
 
 def dist_info_requirement(name):
-    return "@@%%NAME%%//:" + _clean_name(name) + "_dist_info"
+    return "%%MACRO_TMPL%%".format(_clean_name(name), "dist_info")