* 10614: Add pre-commit hook for including the MPLv2
Adds to Python, JS, SCSS, Jinja HTML, Fluent templates and shell scripts
Note that the order of application of the hooks is important - we want to add a missing license before we check the formatting of files
* 10614: Update MPLv2 comments on all templates to match standard format produced by pre-commit hook
* Updates existing MPLv2 text to use a https URL
* Amend a handful of Fluent templates that used a token instead of the string "Mozilla" - this standardised things; translation was not used or needed
* Add missing MPLv2 where needed
* Update three tests that regressed with these changes, above
* 10614: Update pre-commit config to not add MPL to JS libraries; Remove MPL from the four files which should not have had it
* Update requirements to avoid requests version clash
* 10570: Add isort to project
* 10570: Add isort config to project
* 10570: Add isort as a test run/CI step
* 10570: Add isort to pre-commit config
* 10570: Update isort config to allow tests/pages.py to be first-party, which is more appropriate
* 10570: Apply isort to entire codebase, using project config
* 10570: Explicitly include lib/ as a first-party import
This behaviour is already implicit in the current config, but making it explicit, partly to protect against a future change. Also makes it easier to grok what will happen to various bedrock-codebase imports
* 10570: Update isort config to stack Django imports above third-party ones
* 10570: [nit-fix] Update run-tests.sh to call isort with the same syntax pattern as we call black