Make the consolidated isloopclosed writable

[mikelangmayr]

• on multi-stage modules (LSM, MS) the module-level isloopclosed was read-only, so libby modify hsfei.lsm.isloopclosed=true was rejected even though isreferenced accepts a write and piaa-gimbalmount already allows writing its module-level isloopclosed
• it now sets the loop on every stage, mirroring _set_all_referenced
• extracted _Stage.set_loop_closed from the inline lambda so the per-axis keyword and the consolidated one call the same code, matching how the getters were already factored
• verified against a live broker with a mocked controller: the consolidated keyword reports readonly False, a write reaches close_loop on each stage with the right device and enable flag, and single-stage configs still register exactly one isloopclosed with its per-axis setter intact