Adds

• Add explicit error messages for missing package extras during import
• Better browser abstraction:
  • BrowserController - Wraps a single browser instance and maintains its state.
  • BrowserPlugin - Manages the browser automation framework, and basically acts as a factory for controllers.
• Browser rotation with a maximum number of pages opened per browser.
• Add emit persist state event to event manager
• Add batched request addition in RequestQueue
• Add start requests option to BasicCrawler
• Add storage-related helpers get_data, push_data and export_to to BasicCrawler and BasicContext
• Add PlaywrightCrawler's enqueue links helper

Fixes

• Fix type error in persist state of statistics