docs: resurface googleapis.dev and prediction docs (#1724)

I've mistakenly broken some of the docs for types links on googleapis.dev. Fixing the docs structure so the docs are showing again. If you run `nox -s docs` and take a look around the docs, they'll be back up.

I've verified that prediction pages are back up on c.g.c.

- [x] Make sure to open an issue as a [bug/issue](https://togithub.com/googleapis/python-aiplatform/issues/new/choose) before writing your code!  That way we can discuss the change, evaluate designs, and agree on the general idea
- [x] Ensure the tests and linter pass
- [x] Code coverage does not decrease (if any source code was changed)
- [x] Appropriate docs were updated (if necessary)

Fixes #1722 🦕

Author: dandhlee

docs/aiplatform/definition_v1/types.rst docs/aiplatform/definition_v1.rst

@@ -280,7 +280,12 @@ def docs(session):
     """Build the docs for this library."""
 
     session.install("-e", ".")
-    session.install("sphinx==4.0.1", "alabaster", "recommonmark")
+    session.install(
+        "sphinx==4.0.1",
+        "alabaster",
+        "google-cloud-aiplatform[prediction]",
+        "recommonmark",
+    )
 
     shutil.rmtree(os.path.join("docs", "_build"), ignore_errors=True)
     session.run(
@@ -302,7 +307,11 @@ def docfx(session):
 
     session.install("-e", ".")
     session.install(
-        "sphinx==4.0.1", "alabaster", "recommonmark", "gcp-sphinx-docfx-yaml"
+        "sphinx==4.0.1",
+        "alabaster",
+        "google-cloud-aiplatform[prediction]",
+        "recommonmark",
+        "gcp-sphinx-docfx-yaml",
     )
 
     shutil.rmtree(os.path.join("docs", "_build"), ignore_errors=True)

docs/aiplatform/definition_v1beta1/types.rst docs/aiplatform/definition_v1beta1.rst

@@ -142,4 +142,11 @@
 # Don't include tests in calculation of test coverage
 s.replace("noxfile.py", """        \"--cov=tests/unit\",""", "")
 
+# Include prediction to be installed for documentation.
+s.replace(
+    "noxfile.py",
+    "\"alabaster\"",
+    "\"alabaster\", \"google-cloud-aiplatform[prediction]\"",
+)
+
 s.shell.run(["nox", "-s", "blacken"], hide_output=False)