Fix launch_server, to be able to use persistent_context and user_data_dir

[pierorolando1]

Issue #253

When attempting to use persistent_context and user_data_dir parameters in launch_server():

launch_server(
    # ...
    persistent_context=True,
    user_data_dir='my-user-data-dir'
    # ...
)

These parameters are completely ignored - they are not read, parsed, or taken into account by the implementation.

Solution

According to playwright-core/src/browserServerImpl.ts, the underlying implementation supports passing _userDataDir for persistent contexts.

This PR adds support for these parameters in launch_server() to enable persistent context functionality when launching browser servers.