list_transfers to take an AssetFilter and an optional txid

[dcorral]

Breaking change to list_transfers, replacing the asset_id: Option parameter (where None meant "transfers not connected to a specific asset") with two explicit parameters:

• filter: AssetFilter. Any (all transfers), NoAsset (transfers not connected to a specific asset, the old None behavior), or Id(asset_id) (the old Some behavior, still validated with AssetNotFound)
• txid: Option. When set, restricts the result to the transfers committed by that on-chain transaction; combined with an asset filter it acts as an intersection; an unknown txid returns an empty list

This makes it possible to look up the transfers behind a given on-chain transaction without listing per asset and filtering client-side.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 96.24%. Comparing base (03f6068) to head (ecb9842).

Additional details and impacted files

@@           Coverage Diff           @@
##           master      #97   +/-   ##
=======================================
  Coverage   96.23%   96.24%           
=======================================
  Files          24       24           
  Lines       13396    13418   +22     
=======================================
+ Hits        12892    12914   +22     
  Misses        504      504           

Flag	Coverage Δ
rust	96.24% <100.00%> (+<0.01%)	⬆️

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[zoedberg]

Thanks! Please address the requested changes

[zoedberg]

let's use db_data, to avoid the extra query

note that this change will make you revert the ones you did to src/database/mod.rs

[zoedberg]

LGTM, thank you!