Add control-policy mappings and rename control APIs

This introduces the ability to map controls to policies alongside the
existing control-mitigation mappings. The feature adds bidirectional
relationships with new GraphQL fields on Control and Policy types.

Signed-off-by: gearnode <bryan@frimin.fr>

pkg/coredata/migrations/20250408T205600Z.sql

@@ -0,0 +1,7 @@
+CREATE TABLE controls_policies (
+    control_id TEXT NOT NULL REFERENCES controls(id),
+    policy_id TEXT NOT NULL REFERENCES policies(id),
+    tenant_id TEXT NOT NULL,
+    created_at TIMESTAMP WITH TIME ZONE NOT NULL,
+    PRIMARY KEY (control_id, policy_id)
+);