Phablytics

- updates Flask (>=2.1.3) and Flask-WTF (1.0.*)

- move revision statuses to constants
- refactors and DRYs up report generation with `ReportSectionConfig`
- adds WIP diffs section to RevisionStatusReport
- adds flag `include_in_slack` for sections to include in Slack

- Updates to use explicitly set Conduit API token, Phabricator base URL, etc
- Adds `/users` listing page and user profile page
- Adds utils for fetching users: single user by user name, multiple users, all active users
- Adds the ability to show metrics for specific users
- Adds more colors from flatuicolors.com
- Upgrades to Chart.js 3.8.0 and adds legend event hooks
- cleanup: rename `*_pages` to `*_endpoints` for several view

- Fixes breadcrumbs for report names by preserving case

- Removes an incorrect type hint

- Fixes metric aggregation by customer, service, and owner (12)
- Fixes `start_of_month` by simply using `1`, instead of `calendar.monthrange[0]`, (11)
- Minor improvements to metrics explorer (10)
- adds `CUSTOM_STATIC_DIR` and `CUSTOM_STYLESHEETS` served by `{{ url_for('custom_static', filename=filename) }}` (9)