Refactor Sphinx setup with separated imports and setup macros

- Created gapic/templates/docs/common_setup.py.j2 with sphinx_imports and sphinx_setup macros
- Updated gapic/templates/docs/conf.py.j2 to call imports at top and setup at bottom
- Updated gapic/ads-templates/docs/conf.py.j2 similarly

Author: google-labs-jules[bot]

gapic/ads-templates/docs/conf.py.j2

@@ -1,7 +1,7 @@
 {% extends '_base.py.j2' %}
 
 {% block content %}
-{% from "docs/common_setup.py.j2" import sphinx_setup %}
+{% from "docs/common_setup.py.j2" import sphinx_imports, sphinx_setup %}
 
 #
 # {{ api.naming.warehouse_package_name }} documentation build configuration file
@@ -18,6 +18,7 @@
 import sys
 import os
 import shlex
+{{ sphinx_imports() }}
 
 # If extensions (or modules to document with autodoc) are in another directory,
 # add these directories to sys.path here. If the directory is relative to the

gapic/templates/docs/common_setup.py.j2

@@ -1,7 +1,9 @@
-{% macro sphinx_setup() -%}
+{% macro sphinx_imports() -%}
 import logging
 from typing import Any
+{%- endmacro %}
 
+{% macro sphinx_setup() -%}
 class UnexpectedUnindentFilter(logging.Filter):
     """Filter out warnings about unexpected unindentation following bullet lists."""
 

gapic/templates/docs/conf.py.j2

@@ -1,7 +1,7 @@
 {% extends '_base.py.j2' %}
 
 {% block content %}
-{% from "docs/common_setup.py.j2" import sphinx_setup %}
+{% from "docs/common_setup.py.j2" import sphinx_imports, sphinx_setup %}
 
 #
 # {{ api.naming.warehouse_package_name }} documentation build configuration file
@@ -18,6 +18,7 @@
 import sys
 import os
 import shlex
+{{ sphinx_imports() }}
 
 # If extensions (or modules to document with autodoc) are in another directory,
 # add these directories to sys.path here. If the directory is relative to the