feat: Handle balances when using Bank Sync

[bvanelli]

Allows the accounts to be reconciled when doing the first bank sync. This happens when the expected balance of the account does not match the final balance of the imported transactions, because old transactions are not imported.

This should only affect the first import using the bank sync, or if all transactions are deleted and a new bank sync is done.

Either way, it manages to reproduce 1:1 what we find on the simpleFin demo dataset, when importing from Actual or actualpy.

Closes #29

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 97.90%. Comparing base (d2f2878) to head (19d9662).
Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #108      +/-   ##
==========================================
+ Coverage   97.89%   97.90%   +0.01%     
==========================================
  Files          16       16              
  Lines        2283     2295      +12     
==========================================
+ Hits         2235     2247      +12     
  Misses         48       48              

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