[TASK] Revert when no change happens in a state-changing function

[alainncls]

Title: Ensure State-Changing Functions Revert When No Actual State Change Occurs

Description:
Several state-changing functions in the codebase succeed and emit events even when no actual state change occurs. This can lead to misleading events being emitted, which may confuse off-chain consumers relying on event data to track on-chain activity. Additionally, allowing such calls to succeed provides no meaningful benefit and could indicate a mistake by the caller.

Examples:

1. setIssuer function (PortalRegistry)

   • Emits an IssuerAdded event even if the issuer address is already registered as an issuer.
   • Code Reference: contracts/src/PortalRegistry.sol:L87-L96

2. removeIssuer function (PortalRegistry)

   • Emits an IssuerRemoved event even if the issuer address is not an issuer.
   • Code Reference: contracts/src/PortalRegistry.sol:L107-L115

3. updateRouter function (AttestationRegistry and similar contracts)

   • Emits a RouterUpdated event even if the router address doesn’t actually change.
   • Code References:
     • contracts/src/AttestationRegistry.sol:L82-L90
     • contracts/src/ModuleRegistry.sol:L72-L80
     • contracts/src/PortalRegistry.sol:L78-L86
     • contracts/src/SchemaRegistry.sol:L83-L91

Task:
Update the implementation of the affected functions (and any other similar functions) to revert when no actual state change would take place.