Port to Lomiri on focal

• port to Lomiri
• update Click packaging
• restore Debian packaging for focal
• rename package and application by removing ubuntu- prefix
• restore tests
• update and move Jenkinsfile to debian/
• update .pot file

This fixes #213 (closed).

Current review errors:

- online_accounts:account-application_hook:calendar
'account-application' is disallowed in ubuntu-sdk-20.04: use 'accounts' hook instead
- online_accounts:account-application_services:calendar
Could not find '<services>' tag

See clickable/click-reviewers-tools#5 (closed).

- security:policy_groups_safe:calendar:calendar
(NEEDS REVIEW) reserved policy group 'calendar': vetted applications only
- security:policy_groups_safe:calendar:contacts
(NEEDS REVIEW) reserved policy group 'contacts': vetted applications only
- security:redflag_fields:com.ubports.calendar.apparmor
found redflagged fields (needs human review): read_path

These have not changed.