Add config_and_tools and featuretoggles Sphinx extension

See https://github.com/edx/code-annotations/blob/master/CHANGELOG.rst#050---2020-08-06

Add support for multi-line code annotations

Added support for multi-line code annotations.

Django and Python support updated

• Removed Support for python2.7 and python3.6.
• Removed support for Django<2.2.
• Added support for Python3.8.

v0.3.3

Compatibility with django 2.

v0.3.2

Add RST anchors to each annotation group in generated reports.

v0.3.1

Bump several dependencies, notably pyyaml to 5.1

v0.3

• Adds the ability to generate human readable reports in RST from code-annotations generated YAML files

v0.2.4

• Added prefixing of Django model PII report with application name optionally.
• Fixed the elapsed time output at end of django_find_annotations.

v0.2.2

Documentation updates and a bug fix to default safelist generation.

v0.2.1

Fixes an issue with coverage reporting on safelisted Django models and improves documentation around the necessity of annotating in the safelist.