[Feature]: Add target DKG rounds configuration parameter

[cylewitruk]

Feature - Add target DKG rounds configuration parameter

1. Description

Add a new configuration parameter for specifying the target (i.e. max) number of DKG rounds that can be performed (#1199) or accepted (#1200) by the sBTC signer.

1.1 Context & Purpose

We want to support full DKG. But that is difficult so we are tackling it in phases. Phase 0 was running DKG once. Phase 1 was supporting DKG a second time, and this ticket is part of phase 1.

2. Technical Details:

Add a new optional signer config variable for the second DKG run. For the example production configs, set the target to 2. The default for this parameter should be 1 to prevent an accidental mis-configuration (or lack of setting this value) by signer partners from accidentally allowing unbounded DKG runs.

2.1 Acceptance Criteria:

• We have a required configuration variable for the second DKG run.

3. Related Issues and Pull Requests (optional):

This relates to #1200, #1199 and #1152, which together add support for the second DKG run.