Switch to using diff-cover for the Coverage gate (#33673)

* Switch to using diff-cover for the Coverage gate

Enabling developers to check their PR coverage without waiting for CI

* Remove sonar-project.properties - in automatic mode Sonar will not read this file

* Add note to CONTRIBUTING.md

* Skip sonar in MQ

apps/desktop/package.json

@@ -54,6 +54,8 @@
         "test:playwright": "nx test:playwright --",
         "test:playwright:open": "nx test:playwright -- --ui",
         "test:playwright:screenshots": "nx test:playwright:screenshots --",
+        "coverage": "pnpm test:unit --coverage",
+        "coverage:diff": "diff-cover --config-file ../../diff-cover.toml coverage/lcov.info",
         "sane-postinstall": "electron-builder install-app-deps"
     },
     "dependencies": {
@@ -106,8 +108,7 @@
         "rimraf": "^6.0.0",
         "tar": "^7.5.8",
         "typescript": "6.0.3",
-        "vitest": "catalog:",
-        "vitest-sonar-reporter": "catalog:"
+        "vitest": "catalog:"
     },
     "hakDependencies": {
         "matrix-seshat": "4.3.0"