support l2cap/psm socket connections

[travisghansen]

Is your feature request related to a problem? Please describe.
I'm hoping to create a socket using l2cap/psm. I'm pretty new to ble but it seems this is missing from the project?

Describe the solution you'd like
I want to be able to setup a socket for long-running bits of data flowing back and forth (effectively a ble version of a websocket if you will).

Describe alternatives you've considered
I'm prototyping both client/server using this: https://github.com/Emill/node-ble-host?tab=readme-ov-file#l2cap-connection-oriented-channels

Perhaps relevant info:

• https://developer.chrome.com/docs/apps/app_bluetooth#using_rfcomm
• https://stackoverflow.com/questions/65768590/transmit-binary-file-to-device-using-ble