[BREAK] Remove old migrations up to version 2.4.14

[sampaiodiego]

Proposed changes (including videos or screenshots)

To update to version 4.0.0 you'll need to be running at least version 3.0.0, otherwise you might loose some database migrations which might have unexpected effects.

This aims to clean up the code, since upgrades jumping 2 major versions are too risky and hard to maintain, we'll keep only migration from that last major (in this case 3.x).

Another changes included in this PR:

• Removed old Migrations class - functionality remains the same though
  • New migrations should use addMigration() instead of Migrations.add()
• Migrations code re-written in TS

Still missing some code clean up.

Issue(s)

Steps to test or reproduce

Further comments

[lgtm-com]

This pull request fixes 4 alerts when merging 650005a into 88b2698 - view on LGTM.com

fixed alerts:

• 3 for Insecure randomness
• 1 for Useless assignment to local variable

[geekgonecrazy]

@debdutdeb This one is one you will want to pay attention to from snap perspective. Gotta make sure every snap update goes through a 3.x version no matter what they chose to do by staying back a version on an old track like 1.x or 2.x 🙏

[edit]
Also brought up internal but maybe we shouldn't even start if current migration is older then the latest one here?