[native] Set SQLite DB password to DEBUG for DEBUG builds

Summary:
Interacting with the SQLite DB can be a huge pain since the path and password change on every clean install.

In the past, if you wanted to open a SQLite DB in TablePlus/DataGrip/etc, you needed to add some logging that printed SQLiteQueryExecutor::encryptionKey in addition to the DB PATH. This makes it easier and harcodes the password to DEBUG for DEBUG builds.

Test Plan: Tested iOS debug/release build and observed that DEBUG unlocked the SQLite DB under debug, but NOT under release.

Reviewers: ashoat, marcin, bartek, rohan

Reviewed By: ashoat

Subscribers: tomek

Differential Revision: https://phab.comm.dev/D7243