feat(api): add relativeModuleId to TestModule (#8505)

Author: sheremet-va

docs/advanced/api/test-module.md

@@ -24,6 +24,16 @@ This is usually an absolute unix file path (even on Windows). It can be a virtua
 'C:\\Users\\Documents\\project\\example.test.ts' // ❌
 ```
 
+## relativeModuleId
+
+Module id relative to the project. This is the same as `task.name` in the deprecated API.
+
+```ts
+'project/example.test.ts' // ✅
+'example.test.ts' // ✅
+'project\\example.test.ts' // ❌
+```
+
 ## state
 
 ```ts

packages/vitest/src/node/reporters/reported-tasks.ts

@@ -437,10 +437,16 @@ export class TestModule extends SuiteImplementation {
    */
   public readonly moduleId: string
 
+  /**
+   * Module id relative to the project. This is the same as `task.name`.
+   */
+  public readonly relativeModuleId: string
+
   /** @internal */
   protected constructor(task: RunnerTestFile, project: TestProject) {
     super(task, project)
     this.moduleId = task.filepath
+    this.relativeModuleId = task.name
   }
 
   /**