[Feature] Allow proxy for ConnectAsync and ConnectOverCdpAsync

[Refreshmant]

My employer (an enterprise organization) requires most outgoing traffic to use a proxy.
One of our requirements is to connect to an existing browser that hosted outside our network. (i.e. BrowserStack)

Currently it's not possible to configure a proxy when using the BrowserType.ConnectAsync and BrowserType.ConnectOverCdpAsync methods.
A workaround is available when using node by using a npm package to configure the proxy, but I haven’t found a similar solution for the .net version.

I’ve also found similar issues but these don’t seem to apply to my case.

• Unable to pass Proxy over ConnectAsync
• How to use proxy with ConnectOverCDPAsync

[Max Schmitt]

Folding into microsoft/playwright#26985.