feat: chain agnostic

[chris13524]

Description

• Implements behavior for treating any account the same as long as it has the same address. This works by using the get_address_lower() function when doing SQL queries.
  • An alternative approach is to migrate the database so that it only stores address and not the full account ID. While this would simplify queries and probably be simpler overall, I decided to keep the current format as this is a risky change overall and the chain info may be needed in the future (for example with smart contract support or namespace identification).
• For now assumes eip155 account IDs
  • Manually confirmed that all accounts are currently eip155
  • This is enforced going forward with is_eip155_account() in the verify_identity() function
• Implements migration to delete subscribers with the same address, prior to adding the new unique constraint. This keeps the subscription with the most notifications.
• Fix security issue where delete subscription requests do not verify that the account matches the looked up subscriber. Added explicit is_same_address() check. This was not a high-risk issue because it required already knowing the symmetric key of the topic, which is private information anyway.
  • Refactor update_subscriber() parameters to take subscriber ID instead of project and account, to simplify, improve performance, and reduce risk of security vulnerabilities (i.e. using the same subscriber that was looked up earlier in the function)
• Refactor upsert_subscriber() to also return account of the subscriber so that analytics can export a consistent account regardless of which account was used for the request

Resolves #265

How Has This Been Tested?

New automated tests

Due Diligence

• Breaking change
• Requires a documentation update
• Requires a e2e/integration test update

[geekbrother]

lgtm. I think it's better to migrate the existing database and safer.