Add request event handling on BrowserContext

[randall-coding]

Description

This is a small fix for handling request events. Request events come in through the BrowserContext object on the subscribe_event() function but the current rust code is expecting it on the Page object which cannot receive those events based on the current implementation.

For reference we can look at how playwright-java handles these events (in the BrowserContextImpl.java and PageImpl.java files). I think we are forced to do it this way based on what the playwright driver is sending to us, though I'm not 100% sure since I'm still learning this codebase.

My changes

I added request event handling to the imp/BrowserContext.rs class and updated all related files needed to catch and rely the event.

Warning

This contains code from another pull request that updates the driver version (see PR #26).