[BUILDER] - Orchestrator supports builder

[elliedavidson]

What is this task and why do we need to work on it?

The orchestrator needs to wait for the builder(s) to start before signaling the entire network to start. But the builder is a non-staked node and therefore should not be given a node index.

What work will need to be done to complete this task?

Proposed design:

• Add a "builders" field to the HotShot config and have the orchestrator wait for all nodes to signal start as well as all builders.

Other proposed design:

• Give the builder a node index, but clarify it as a "listening only" node.

May need more discussion on how we want to support non-voting nodes in general.

Are there any other details to include?

See discussion here

cc @nyospe and @move47 for visibility

What are the acceptance criteria to close this issue?

Start a small network with at least 1 builder present. Confirm that the builder is not assigned a node index.

Branch work will be merged to (if not the default branch)

No response

[move47]

Some work was done in #2721.