Add a DAP server for IDEs to interact with

[sdankel]

We should add a command like forc debug serve that starts a DAP server for the LSP to communicate with. The server will be essentially a passthrough to the fuel core client, which has DAP-like APIs in its graphql interface.

The IDE extensions can then use the same binary to start the DAP server, so the user only has to have 1 binary for both CLI-based debugging and IDE-based.