chore(py_executable): print warning if build zip is enabled (#3568)

This prints a warning if `--build_python_zip` is enabled.

Work towards #3567
#2586

Author: rickeylev

CHANGELOG.md

@@ -58,6 +58,15 @@ END_UNRELEASED_TEMPLATE
 
 {#v0-0-0-changed}
 ### Changed
+* **DEPRECATED: implicit zipapp support**
+  * Implicit zipapp output of `py_binary`/`py_test` has been deprecated and
+    replaced by separate {obj}`py_zipapp_binary` and {obj}`py_zipapp_test`
+    rules. See
+    [#3567](https://github.com/bazel-contrib/rules_python/issues/3567)
+    for a detailed migration guide.
+* (toolchains) stop exposing config settings in python toolchain alias repos.
+  Please consider depending on the flags defined in
+  `//python/config_setting/...` and the `@platforms` package instead.
 * (binaries/tests) The `PYTHONBREAKPOINT` environment variable is automatically inherited
 * (binaries/tests) The {obj}`stamp` attribute now transitions the Bazel builtin
   {obj}`--stamp` flag.

python/private/py_executable.bzl

@@ -379,6 +379,21 @@ def _create_executable(
     # When --build_python_zip is enabled, then the zip file becomes
     # one of the default outputs.
     if build_zip_enabled:
+        # buildifier: disable=print
+        print(
+            """
+======================================================================
+WARNING: Target: {}
+  The `--build_python_zip` flag and implicit zipapp output of `py_binary`
+  and `py_test` is deprecated and will be removed in a future release.
+  Switch to `py_zipapp_binary` or `py_zipapp_test`. For migration
+  instructions and guide, see:
+
+  https://github.com/bazel-contrib/rules_python/issues/3567
+======================================================================
+               """.rstrip().format(ctx.label),
+        )
+
         extra_default_outputs.append(zip_file)
 
     # The logic here is a bit convoluted. Essentially, there are 3 types of