hw/vfio/container.c: rename file to container-legacy.c

This file is mostly concerned with the VFIOLegacyContainer implementation so
rename it to reflect the previous rename of VFIOContainer to
VFIOLegacyContainer.

Signed-off-by: Mark Cave-Ayland <mark.caveayland@nutanix.com>
Reviewed-by: Cédric Le Goater <clg@redhat.com>
Link: https://lore.kernel.org/qemu-devel/20250925113159.1760317-6-mark.caveayland@nutanix.com
Signed-off-by: Cédric Le Goater <clg@redhat.com>

hw/vfio/meson.build

@@ -4,7 +4,7 @@ vfio_ss = ss.source_set()
 vfio_ss.add(files(
   'listener.c',
   'container-base.c',
-  'container.c',
+  'container-legacy.c',
   'helpers.c',
 ))
 vfio_ss.add(when: 'CONFIG_PSERIES', if_true: files('spapr.c'))