Kart doesn't include SRID when writing features to the WC during kart resolve

[olsen232]

Originally kart resolve didn't keep the WC up to date during merge conflict resolution at all.
As part of relatively recent changes needed for tile-based datasets, the working copy is now a more useful part of merge conflict resolution, and is kept up to date as each resolution is applied by kart resolve.

Kart doesn't store SRIDs per row - they are only stored once per geometry column (in effect, once per table).
During working copy checkout, SRIDs have to be added to each feature (if the working copy type expects them to be embedded in every geometry in every row). The code to do this when writing a single resolution to the WC during kart resolve was missing, which may or may not cause issues depending on how lenient the WC is to missing SRIDs.

Originally filed as koordinates/kart-qgis-plugin#100

[olsen232]

Fixed with #841