Add djangorestframework-stubs for better typing

[tdrivas]

This PR introduces the following updates to enhance type checking in our project:

• Integrate mypy by adding mypy_drf_plugin to mypy.ini for better Django REST Framework type-checking.
• Integrate pre-commit by updating .pre-commit-config.yaml to ensure mypy runs with pre-commit using the new plugin and settings.
• Add djangorestframework-stubs to the requirements.in file in order to regenerate the appropriate requirements.txt
• Fix various typing issues such as type mismatches in exception, and incorrect annonations

Examples of issues:

1. from rest_framework.views import View --> The mypy-drf-plugin is strict about ensuring attributes or classes explicitly exported by a module. In simply words, mypy complains because it’s not officially listed in the all attribute of the rest_framework.views module.

[duke-nyuki]

Task linked: QF-4916 Add djangorestframework-stubs for better typing

[suricactus]

Thanks! Please squash all the commits into a single one and rebase on latest master. Then I will merge after second check.

[suricactus]

Thanks!