Add fake GenTL fixtures and gentl backend tests

Introduce a lightweight, SDK-free fake GenTL/Harvesters implementation and associated pytest fixtures to enable strict lifecycle unit tests for the gentl backend. Replaces the old _DeviceInfoAdapter with a robust attribute/dict reader (_info_get), implements _FakeNode/_FakeNodeMap/_FakeComponent/_FakePayload and a dataclass FakeImageAcquirer with strict start/fetch semantics and call tracing. Adds FakeHarvester with inventory-driven device_info_list, create/create_image_acquirer compatibility and call recording, plus fixtures gentl_inventory, fake_harvester_factory, patch_gentl_sdk (patches backend to use fakes) and gentl_settings_factory. Also adds tests/cameras/backends/test_gentl_backend.py with comprehensive unit tests covering open/read/close, fast_start behavior, device selection (serial/fingerprint), rebind_settings, discover_devices, resolution alignment, pixel format handling, and other edge cases to validate the gentl backend behavior.

Author: C-Achard

.coveragerc

@@ -3,7 +3,4 @@
 [run]
 branch = True
 source = dlclivegui
-omit =
-    # omit only the parts that are pure passthrough shims to SDKs
-    dlclivegui/cameras/backends/basler_backend.py
-    dlclivegui/cameras/backends/gentl_backend.py
+# omit =