pw_unit_test: Standardize Bazel interface

* Use only //pw_unit_test:pw_unit_test to expose framework.h.
* Provide a dependency on this target automatically to any pw_cc_test.

The latter change is made via an alias, to avoid breaking any users who
already have an explicit dep on this target in their pw_cc_test. (Trying
to remove this dep from the list of deps is unreliable, because the deps
may include select statements.) In subsequent CLs, I'll remove all
explicit deps on //pw_unit_test:pw_unit_test, and clean up the alias.

Bug: 390709187
Change-Id: Id3d18ddfd94e69cb51a4f7ff3485c237b85a0dbf
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/261395
Lint: Lint 🤖 <[email protected]>
Reviewed-by: Armando Montanez <[email protected]>
Presubmit-Verified: CQ Bot Account <[email protected]>
Commit-Queue: Ted Pudlik <[email protected]>
Docs-Not-Needed: Ted Pudlik <[email protected]>

pw_unit_test/BUILD.bazel

@@ -63,6 +63,13 @@ pw_facade(
     deps = [":status_macros"],
 )
 
+# TODO: https://pwbug.dev/390709187 - Remove this alias once no pw_cc_test has
+# an explicit direct dependency on //pw_unit_test.
+alias(
+    name = "pw_unit_test_alias_for_migration_only",
+    actual = "pw_unit_test",
+)
+
 label_flag(
     name = "backend",
     build_setting_default = ":light",
@@ -89,21 +96,16 @@ cc_library(
     srcs = ["framework_light.cc"],
     hdrs = [
         "light_public_overrides/pw_unit_test/framework_backend.h",
-        # The facade header is included here since
-        # public_overrides/gtest/gtest.h includes it. This avoids a circular
-        # dependency in the build system.
-        "public/pw_unit_test/framework.h",
         "public_overrides/gtest/gtest.h",
     ],
     includes = [
         "light_public_overrides",
-        "public",
         "public_overrides",
     ],
     deps = [
         ":config",
         ":event_handler",
-        ":status_macros",
+        ":pw_unit_test.facade",
         "//pw_assert",
         "//pw_bytes:alignment",
         "//pw_polyfill",

pw_unit_test/pw_cc_test.bzl

@@ -34,10 +34,10 @@ def pw_cc_test(**kwargs):
     Args:
       **kwargs: Passed to cc_test.
     """
-    kwargs["deps"] = kwargs.get("deps", []) + [str(Label("//pw_build:default_link_extra_lib"))]
-
-    # Depend on the backend. E.g. to pull in gtest.h include paths.
-    kwargs["deps"] = kwargs["deps"] + [str(Label("//pw_unit_test:backend"))]
+    kwargs["deps"] = kwargs.get("deps", []) + [
+        str(Label("//pw_build:default_link_extra_lib")),
+        str(Label("//pw_unit_test:pw_unit_test_alias_for_migration_only")),
+    ]
 
     # Save the base set of deps minus pw_unit_test:main for the .lib target.
     original_deps = kwargs["deps"]