Add mechanism to check only one instance of the app is running (#11416)

* Add mechanism to check only one instance of the app is running

This isn't used yet, but will form part of the solution to
https://github.com/vector-im/element-web/issues/25157.

* disable instrumentation for SessionLock

* disable coverage reporting

* exclude SessionLock in sonar.properties

* Revert "disable coverage reporting"

This reverts commit 80c4336f76.

* only disable session storage

* use pagehide instead of visibilitychange

* Add `checkSessionLockFree`

* Give up waiting for a lock immediately when someone else claims

* Update src/utils/SessionLock.ts

jest.config.ts

@@ -36,7 +36,12 @@ const config: Config = {
         "RecorderWorklet": "<rootDir>/__mocks__/empty.js",
     },
     transformIgnorePatterns: ["/node_modules/(?!matrix-js-sdk).+$"],
-    collectCoverageFrom: ["<rootDir>/src/**/*.{js,ts,tsx}"],
+    collectCoverageFrom: [
+        "<rootDir>/src/**/*.{js,ts,tsx}",
+        // getSessionLock is piped into a different JS context via stringification, and the coverage functionality is
+        // not available in that contest. So, turn off coverage instrumentation for it.
+        "!<rootDir>/src/utils/SessionLock.ts",
+    ],
     coverageReporters: ["text-summary", "lcov"],
     testResultsProcessor: "@casualbot/jest-sonar-reporter",
 };