feat: Firebase Performance - add support for attributes for custom traces

[sachingarg05]

Firebase supports adding attributes to traces.
https://firebase.google.com/docs/perf-mon/custom-code-traces?platform=ios#create-custom-attributes

It will be great if the start_trace API is extended to support an optional attributes parameter that is an array of attributes to attach to the trace.

Something like:
await FirebasePerformance.startTrace({ traceName: 'test_trace', attributes: ['attrib1', 'attribe2'] });

The logEvent API already supports somethings similar:

await FirebaseAnalytics.logEvent({
    name: 'sign_up',
    params: { method: 'password' },
  });

[robingenz]

I close this issue as duplicate of #505