fix: add explicit err msgs for missing pckg extras during import

[vdusek]

Description

• Add explicit error messages for missing package extras during import.
• It applies to BrowserPool, BeautifulsoupCrawler, and PlaywrightCrawler.
• Also until now the Playwright was mandatory for even BasicCrawler, fixing it.

Related issues

• Closes Improve error message when importing missing package extras #155

Testing

PlaywrightCrawler

ImportError                               Traceback (most recent call last)
Cell In[3], line 1
----> 1 from crawlee.playwright_crawler import PlaywrightCrawler

File ~/Projects/crawlee-py/src/crawlee/playwright_crawler/__init__.py:5
      3     from .types import PlaywrightCrawlingContext
      4 except ImportError as exc:
----> 5     raise ImportError(
      6         'To use this module, you need to install the "playwright" extra. Run "pip install crawlee[playwright]".',
      7     ) from exc

ImportError: To use this module, you need to install the "playwright" extra. Run "pip install crawlee[playwright]".

BeautifulsoupCrawler

ImportError                               Traceback (most recent call last)
Cell In[1], line 1
----> 1 from crawlee.beautifulsoup_crawler import BeautifulSoupCrawler

File ~/Projects/crawlee-py/src/crawlee/beautifulsoup_crawler/__init__.py:5
      3     from .types import BeautifulSoupCrawlingContext
      4 except ImportError as exc:
----> 5     raise ImportError(
      6         'To use this module, you need to install the "beautifulsoup" extra. Run "pip install crawlee[beautifulsoup]".',
      7     ) from exc

ImportError: To use this module, you need to install the "beautifulsoup" extra. Run "pip install crawlee[beautifulsoup]".

BrowserPool

ImportError                               Traceback (most recent call last)
Cell In[2], line 1
----> 1 from crawlee.browsers import BrowserPool

File ~/Projects/crawlee-py/src/crawlee/browsers/__init__.py:5
      3     from .playwright_browser_plugin import PlaywrightBrowserPlugin
      4 except ImportError as exc:
----> 5     raise ImportError(
      6         'To use this module, you need to install the "playwright" extra. Run "pip install crawlee[playwright]".',
      7     ) from exc

ImportError: To use this module, you need to install the "playwright" extra. Run "pip install crawlee[playwright]".

Checklist

• Changes are described in the CHANGELOG.md
• CI passed