Remove initialize

[cafalchio]

Initial phase of remove initialize.

• removed initialize
• added a stripped version of initialized per call connect_backend_for_request
• removed session_id from validate
• removed merge and build capabilities
• Added tool call for protocol
• tested tool call using new protocol

Ignore tests for now.

[dawid-nowak]

This is fine but:

1. I would expect the initialize to be gone and return Error when the initialize is somehow needed.
2. We should remove the all traces of connection management etc. we will not need it.