Resolve unfinished pull properly also for subfolders #299

Resolve unfinished pull is not resolving properly geopackages in subfolders. As .mergin/unfinished_pull folder was walking just for files in root.

Reproduce (try in Windows, but it could be harder to reproduce or manually patch the code for raising unfinished pull):

• profile 1: create simple project in plugin
• profile 1: copy Survey_points.gpkg to /Layers/New.gpkg
• profile 1: add /Layers/New.gpkg to qgis layer tree
• profile 1: push
• profile 2: download project
• profile 2: add point Layers/New.gpkg (not sync, just save changes to gpkg)
• profile 1: add column with some random name to /Layers/New.gpkg in qgis to break history of gpkg
• profile 1: copy /Layers/New.gpkg -> New.gpkg to create new gpkg which will create new file in root direcory of project
• profile 1: sync
• profile 2: Settings -> User profiles -> Open active directory -> find python -> plugins -> Mergin -> mergin -> merginproject.py file - add to line 789 following code to simulate unfinished pull:

raise pygeodiff.GeoDiffLibError("conflicted copy created successfully, no need for fallback")

• profile 2: restart qgis to adapt code changes
• profile 2: sync with DataSyncError: 422

Server changes: 

+ New.gpkg
EDIT: Layers/New.gpkg
probably also qgz change

Local changes:

EDIT: Layers/New.gpkg with insert one feature

After fix:

• profile 2: in logs will resolving unfinished pull for Layers/New.gpkg
• profile 2: just conflict copies are in next sync attempt no points added - No data sync error
• profile 2: in Layers/New.gpkg conflicted copy files will be added point