Migrate agent v2 (#16214)

# Introduction
Closes https://github.com/twentyhq/core-team-issues/issues/1980

In this PR we migrate the agent from v1 to v2.

## New FlatRoleTargetByAgentIdMaps
Derivated the `flatRoleTargetMaps` to be building a
`flatRoleTargetByAgentIdMaps` to ease retrieving a roleId to associate
to an agent

## Coverage
Added strong coverage on both failing and successful CRU agents
operations

---------

Co-authored-by: Weiko <corentin@twenty.com>

packages/twenty-front/src/modules/metadata-error-handler/hooks/useMetadataErrorHandler.ts

@@ -25,6 +25,7 @@ export const useMetadataErrorHandler = () => {
     routeTrigger: t`route trigger`,
     role: t`role`,
     roleTarget: t`role target`,
+    agent: t`agent`,
   } as const satisfies Record<AllMetadataName, string>;
 
   const handleMetadataError = useCallback(