[Feature]: _debugMode check environment variable every time debugMode() is called

[peteryongzhong]

🚀 Feature Request

Right now the _debugMode caches the environment variable PWDEBUG the moment playwright is opened. It would be great if debugMode() could check the environment variable everytime.

Example

No response

Motivation

This change means that there would be a way of temporarily setting that environment variable to force playwright to go into debug mode programmatically. It get us some really nice things, for example, access to the console api which can be interacted programmatically.

[mxschmitt]

Please re-file and provide us a clear use-case of why you want to have this behaviour. So far we expect tests running out-of-process so the outside can always set this env.