[DevEx]: Update the timestamp columns across the codebase to use postgres’ timestampz data type

[itsalaidbacklife]

Improvement Summary

Currently, our time-related columns are stored as simple numbers, represented as milliseconds since Epoch. We should update these in both the code and database to use a proper timestamp type so that the values are human readable and so that we avoid limitations on the size of numbers in both postgres int8 and JavaScript types.

Detailed Description

This will require updating frontend, the backend, and migrating the existing database rows to convert the existing values to the new format.

The timezone should be set to EST for all timestamp rows.

At the code level, the three types of changes to look for:

1. Updating the models in api/models so that the time-related attributes have a columnType of timestampz
2. Updating code that consumes or writes to these columns so that it correctly parses them to and from dayjs() instances (where most of the processing logic happens)
3. Checking and revising any queries that compare times to ensure that they still correctly do what they are supposed to do.

In particular, we should check the Season and Match models’ startTime and endTime attributes, and the lockedAt attribute of the Game model. We should update the consumers of those columns, including the StatsController and its associated helpers, the helpers used when the game ends to add the game to its appropriate match, and the lock-game and unlock-game helpers.

Generally we should look for usages of dayjs which are the areas that involve time calculations and ensure those features still work correctly.

For the database migration, we will need to alter the column types and convert the existing values to match the new types, being careful not to corrupt the existing data. For this reason, the migrations will require significant testing.

Note that we should not need to change the existing createdAt and updatedAt columns which are automatically managed by sails