Refactor email composer (#21177)

# Introduction
Gate what connected account can be ingested in case of ai mcp user
workspace agnostic funnel to only the workspace shared connected account

Added a quick win intregration tests on seeded connected accounts ( that
wasn't covered but already protected fix impacts only the mcp )

Refactored the API slightly too

## Notice
This mean there's a breaking change in the product behavior
Whereas before a non user workspace related mcp interaction would might
have fallback on any private user connected account it will now only
search for workspace visible listed ones

packages/twenty-server/src/modules/messaging/message-outbound-manager/resolvers/send-email.resolver.ts

@@ -69,7 +69,7 @@ export class SendEmailResolver {
           files: input.files ?? [],
           inReplyTo: input.inReplyTo,
         },
-        { workspaceId: workspace.id },
+        { workspaceId: workspace.id, userWorkspaceId },
         { attachmentsFileFolder: FileFolder.EmailAttachment },
       );