Speed up profile loading with per-vendor preset caches

Each vendor's system presets are serialized into a <vendor>.opc cache
that the app loads instead of parsing the profile JSONs, falling back
to the parse whenever no cache covers what is installed. Shipped builds
carry the caches instead of the raw profiles, installing and updating
treat a vendor's cache as its installation, and the setup wizard loads
through the same path. Per-platform scripts and CI generate the caches
at build time; tests and a design doc cover the format and its
validation.

tests/libslic3r/CMakeLists.txt

@@ -17,6 +17,7 @@ add_executable(${_TEST_NAME}_tests
     test_preset_bundle_loading.cpp
     test_preset_setting_id.cpp
     test_preset_diff.cpp
+    test_vendor_cache.cpp
     test_elephant_foot_compensation.cpp
     test_geometry.cpp
     test_multimaterial_segmentation.cpp

tests/libslic3r/test_preset_bundle_loading.cpp

@@ -146,7 +146,7 @@ TEST_CASE("Current vendor type tolerates missing printer model", "[Preset][Bundl
 {
     PresetBundle bundle;
 
-    VendorProfile orca_vendor("ORCA");
+    VendorProfile orca_vendor; orca_vendor.id = "ORCA";
     VendorProfile::PrinterModel model;
     model.name = "Orca Test";
     orca_vendor.models.emplace_back(model);