district: Calendar and countdown snippets for HP

district/migrations/0025_auto_20211119_1708.py

district/models.py

district/templates/district/base.html

...ct/templates/district/blocks/homepage_calendar_block.html

district/templates/district/district_home_page.html

shared/templates/shared/calendar_current_events_snippet.html

shared/templates/shared/election_countdown_snippet.html