Herdr Integration OR Let Terminal Thread Init command expose task variables

[MRDGH2821]

Body

What are you proposing?

Integration of Zed's terminal thread with Herdr.
In short I'm looking to sync the currently opened Zed workspace with Herdr's workspace (reuse existing or open new).

OR

Have agent.terminal_init_command setting work as a typical task. That way I get access to Zed's variables which I can use in custom script or zed task.

Why does this matter?

Right now there is no way to open parallel terminal threads. Herdr solves my problem.
So I configured this in zed settings:

{
  "agent": {
    "terminal_init_command": "herdr",
    }
}

I assumed it would create new workspace inside herdr. Turns out it doesn't. I need to explicitly provide workspace path to get the intended effect.

Possible approach

1. Have terminal_init_command accept task name
2. Have a new task hook which is fired when a new terminal thread is opened
3. Have terminal_init_command expose task variables.

[MRDGH2821]

Related - herdrdev/herdr#841 (comment)