Improve desktop security by isolating Electron

Enable `contextIsolation` in Electron to securely expose a limited set
of Node.js APIs to the renderer process. It:

1. Isolates renderer and main process contexts. It ensures that the
   powerful main process functions aren't directly accessible from
   renderer process(es), adding a security boundary.
2. Mitigates remote exploitation risks. By isolating contexts, potential
   malicious code injections in the renderer can't directly reach and
   compromise the main process.
3. Reduces attack surface.
4. Protect against prototype pollution: It prevents tampering of
   JavaScript object prototypes in one context from affecting another
   context, improving app reliability and security.

Supporting changes include:

- Extract environment and system operations classes to the infrastructure
  layer. This removes node dependencies from core domain and application
  code.
- Introduce `ISystemOperations` to encapsulate OS interactions. Use it
  from `CodeRunner` to isolate node API usage.
- Add a preloader script to inject validated environment variables into
  renderer context. This keeps Electron integration details
  encapsulated.
- Add new sanity check to fail fast on issues with preloader injected
  variables.
- Improve test coverage of runtime sanity checks and environment
  components. Move validation logic into separate classes for Single
  Responsibility.
- Improve absent value test case generation.

tests/unit/shared/Stubs/LocationOpsStub.ts

@@ -0,0 +1,40 @@
+import { ILocationOps } from '@/infrastructure/Environment/SystemOperations/ISystemOperations';
+import { StubWithObservableMethodCalls } from './StubWithObservableMethodCalls';
+
+export class LocationOpsStub
+  extends StubWithObservableMethodCalls<ILocationOps>
+  implements ILocationOps {
+  private sequence = new Array<string>();
+
+  private scenarios = new Map<string, string>();
+
+  public withJoinResult(returnValue: string, ...paths: string[]): this {
+    this.scenarios.set(LocationOpsStub.getScenarioKey(paths), returnValue);
+    return this;
+  }
+
+  public withJoinResultSequence(...valuesToReturn: string[]): this {
+    this.sequence.push(...valuesToReturn);
+    this.sequence.reverse();
+    return this;
+  }
+
+  public combinePaths(...pathSegments: string[]): string {
+    this.registerMethodCall({
+      methodName: 'combinePaths',
+      args: pathSegments,
+    });
+    if (this.sequence.length > 0) {
+      return this.sequence.pop();
+    }
+    const key = LocationOpsStub.getScenarioKey(pathSegments);
+    if (!this.scenarios.has(key)) {
+      return pathSegments.join('/PATH-SEGMENT-SEPARATOR/');
+    }
+    return this.scenarios.get(key);
+  }
+
+  private static getScenarioKey(paths: string[]): string {
+    return paths.join('|');
+  }
+}