feat(crawler): add session management and view-source support

Add session_id feature to allow reusing browser pages across multiple crawls.
Add support for view-source: protocol in URL handling.
Fix browser config reference and string formatting issues.
Update examples to demonstrate new session management features.

BREAKING CHANGE: Browser page handling now persists when using session_id

docs/examples/session_id_example.py

@@ -0,0 +1,38 @@
+import asyncio
+from crawl4ai import (
+    AsyncWebCrawler,
+    BrowserConfig,
+    CrawlerRunConfig,
+    DefaultMarkdownGenerator,
+    PruningContentFilter,
+    CrawlResult
+)
+
+                   
+
+async def main():    
+    browser_config = BrowserConfig(
+        headless=False, 
+        verbose=True,
+    )
+    async with AsyncWebCrawler(config=browser_config) as crawler:
+        crawler_config = CrawlerRunConfig(
+            session_id= "hello_world", # This help us to use the same page 
+        )
+        result : CrawlResult = await crawler.arun(
+            url="https://www.helloworld.org", config=crawler_config
+        )
+        # Add a breakpoint here, then you will the page is open and browser is not closed
+        print(result.markdown.raw_markdown[:500])
+        
+        new_config = crawler_config.clone(js_code=["(() => ({'data':'hello'}))()"], js_only=True)
+        result : CrawlResult = await crawler.arun( # This time there is no fetch and this only executes JS in the same opened page
+            url="https://www.helloworld.org", config= new_config
+        )
+        print(result.js_execution_result) # You should see {'data':'hello'} in the console
+        
+        # Get direct access to Playwright paege object. This works only if you use the same session_id and pass same config 
+        page, context = crawler.crawler_strategy.get_page(new_config)
+
+if __name__ == "__main__":
+    asyncio.run(main())