Allow extending `handleTestEvent` in `PlaywrightEnvironment`

[juan-fernandez]

Is your feature request related to a problem? Please describe.
This is specifically a problem for libraries intercepting jest-environment-* libraries to create integrations.

In this specific line:

    async handleTestEvent(event: Event) {
      const { browserName } = this._config
      const { collectCoverage, haveSkippedTests } = this._jestPlaywrightConfig
      const browserType = getBrowserType(browserName)
      //...

we're not calling super.handleTestEvent which would help said libraries.

Describe the solution you'd like
Change to above to

    async handleTestEvent(event: Event) {
      // calling `super.handleTestEvent` in case it's there
      if (super.handleTestEvent) {
        await super.handleTestEvent.apply(this, arguments)
      }
      const { browserName } = this._config
      const { collectCoverage, haveSkippedTests } = this._jestPlaywrightConfig
      const browserType = getBrowserType(browserName)
      //...

This would help:

• in case jest-environment-* libraries decide to implement their own handleTestEvent
• with Datadog's test visibility library, making it easier to integrate both libraries

Describe alternatives you've considered
Calling super.handleTestEvent seems low risk, so no alternatives were considered.

[juan-fernandez]

PR in #822