[Supplier] Delay newly staked Supplier activation until next session

[red-0ne]

Objective

Prevent newly staked Suppliers from being included in an already started Session and delay their "activation" until the next one starts.

Origin Document

If a Supplier stakes mid-session, there is a possibility of having it included in a Session. This might force Gateways and Applications to updates their Sessions Supplier list at each block.

Goals

• Prevent including Suppliers in a Session if this one has already started.
• Save the Gateways and Applications the need to update the active Session's Suppliers at each block.

Deliverables

• A single PR that:
  • Adds a field in the Supplier proto to indicate when it is allowed to be included in Sessions.
  • Use the above info to filter-out Suppliers that are not active yet.

General deliverables

• Comments: Add/update TODOs and comments alongside the source code so it is easier to follow.
• Testing: Add new tests (unit and/or E2E) to the test suite.
• Makefile: Add new targets to the Makefile to make the new functionality easier to use.
• Documentation: Update architectural or development READMEs; use mermaid diagrams where appropriate.

Creator: @red-0ne

[red-0ne]

Completed as per #707