Client agnostic support for the `node-terminal` adapter

[igorlfs]

Hello!

Is your feature request related to a problem? Please describe.

Currently, the node-terminal only works with VS Code (and derivatives), it cannot be used elsewhere. It would be nice to have a proper documentation on what needs to be implemented on the client side to have it working with other clients. Any guidance would be helpful.

In fact, I wonder if the protocol itself wouldn't benefit from having that logic to handle the terminal upstreamed. It would not only help with the implementation of this feature in other clients, but could offer a standardized way to interact with a terminal on the adapter side.

Describe the feature you'd like

Ideally, I believe this feature could be upstreamed to the DAP. If that's out of scope, is it possible to have a well-defined description of what (and potentially, how) to handle the node-terminal on the client side?

Additional context

Related: https://github.com/mfussenegger/nvim-dap/issues/1033