[Feature]: Implement "network.setExtraHeaders" for WebDriver BiDi #38060
Description
🚀 Feature Request
We added this feature in Firefox via https://bugzilla.mozilla.org/show_bug.cgi?id=1979731 and it will be shipped with Firefox 146.
It means that we can get it implemented for WebDriver BiDi in Playwright.
CC @hbenl
Example
No response
Motivation
With its implementation it will be possible to set custom headers that will be automatically applied for network requests.