* switch bootloader to job and add recreate strategy to db
* add comment about recreate strategy
* Add comment about ttl on bootloader
* add comment about Pod vs Job
- Add the CONFIGS_DATABASE_MINIMUM_FLYWAY_MIGRATION_VERSION and JOBS_DATABASE_MINIMUM_FLYWAY_MIGRATION_VERSION. These are env vars that will determine if the database is ready for an application to start.
- Add the CONFIGS_DATABASE_INITIALIZATION_TIMEOUT_MS and the JOBS_DATABASE_INITIALIZATION_TIMEOUT_MS env vars to determine how long an application should wait for the DB before giving up.
- Create the MinimumFlywayMigrationVersionCheck class. This class contains all the assertions to check if 1) a database is initialised. 2) a database meets the minimum migration version.
- Remove all set up operations from the ServerApp. Use MinimumFlywayMigrationVersionCheck operations instead.
- I also had to modify the Databases and BaseDatabaseInstance classes to support connecting to a database with timeouts. We would previously try forever.
- Add Bootloader to the relevant docker files and Kube files.
- Clean up the migration acceptance tests so it's clear what is happening.
