chore: add setup.py for library_generation (#2447)

Python sources in `library_generation` are imported via

https://github.com/googleapis/sdk-platform-java/blob/c1ef755b4d73bdf8fdac6f86cb10834e920c9c43/library_generation/generate_repo.py#L17-L19

This `setup.py` can be used via `python -m pip install .` so running
something like `cd library_generation && python generate_repo.py` can
detect the `library_generation` _package_.

.gitignore

@@ -22,9 +22,9 @@ target/
 .venv
 
 # library generation
-output/
-library_generation/output/
-library_generation/test/output
-library_generation/test/googleapis
-library_generation/test/resources/integration/golden
-showcase/scripts/output/
+**/output/
+**/googleapis
+library_generation/test/**/golden*/
+library_generation/test/resources/test_repo_level_postprocess/
+**/*egg-info/
+**/build/

library_generation/setup.py

@@ -0,0 +1,23 @@
+"""
+Package information of library_generation python scripts
+"""
+
+from setuptools import setup
+
+setup(name='library_generation',
+      version='0.1',
+      package_dir={
+        'library_generation': '.',
+      },
+      package_data={
+          'library_generation': [
+              '*.sh',
+              'templates/*.j2',
+              'gapic-generator-java-wrapper',
+              'requirements.*',
+              'owlbot/src/requirements.*',
+              'owlbot/bin/*.sh',
+              'owlbot/templates/**/*.j2',
+          ],
+      }
+)

library_generation/test/integration_tests.py

@@ -108,6 +108,7 @@ def test_generate_repo(self):
     @classmethod
     def __pull_repo_to(cls, dest: Path, repo: str, committish: str):
         repo_url = f"{repo_prefix}/{repo}"
+        print(f'Cloning repository {repo_url}')
         repo = Repo.clone_from(repo_url, dest)
         repo.git.checkout(committish)