Refactored the performAction method to use async/await.

[rahulptl165]

Fixes: #4365

Refactor performAction and command methods to use async/await.

This PR refactors the performAction and command methods in enablePerformanceMetrics.js to use async/await properly.

Changes Made:

Before :

performAction(callback) {

    if (!this.api.isChrome() && !this.api.isEdge()) {
      const error = new Error('The command .enablePerformanceMetrics() is only supported in Chrome and Edge drivers');
      Logger.error(error);

      return callback(error);
    }

    const {enable = true} = this;

    this.transportActions.enablePerformanceMetrics(enable, callback);
  }

  command(enable, callback) {
    this.enable = enable;

    return super.command(callback);
  }

After :

async performAction() {

    if (!this.api.isChrome() && !this.api.isEdge()) {
      const error = new Error('The command .enablePerformanceMetrics() is only supported in Chrome and Edge drivers');
      Logger.error(error);
      throw error;
    }

    const {enable = true} = this;

    return new Promise((resolve, reject) => {
      this.transportActions.enablePerformanceMetrics(enable, (err, result) => {
        if (err){
          reject(err);
        } else {
          resolve(result);
        }
      });
    });
  }

  async command(enable) {
    this.enable = enable;

    return super.command();
  }

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