feat: add snapshot_lvm_revertable parameter to module interface

Add the snapshot_lvm_revertable parameter to the snapshot module,
allowing users to create revert boot entries for snapshot sets.
This parameter is supported at both the global level and within
snapshot_lvm_set definitions.

A revert boot entry allows booting into a special mode that
automatically merges the snapshot back into the origin volume,
providing a boot-time rollback mechanism for disaster recovery.

Signed-off-by: Todd Gill <tgill@redhat.com>

Author: trgill

library/snapshot.py

@@ -100,6 +100,13 @@
             When set to true, and passed to the 'snapshot' command, the snapshot created will have
             a corresponding boot entry.  The boot entry will be removed when the snapset is removed.
         type: bool
+    snapshot_lvm_revertable:
+        description: Only supported on operating systems that support snapshot manager (snapm).
+            When set to true, and passed to the 'snapshot' command, the snapshot created will have
+            a corresponding revert boot entry. Booting into the revert entry will trigger an automatic
+            revert operation, merging the snapshot back into the origin volume. The revert boot entry
+            will be removed when the snapset is removed.
+        type: bool
     snapshot_lvm_set:
         description: set of volumes
         type: dict
@@ -110,6 +117,9 @@
             bootable:
                 description: create snapshot with boot menu entry (requires snapm)
                 type: bool
+            revertable:
+                description: create snapshot with revert boot menu entry (requires snapm)
+                type: bool
             volumes:
                 description: list of volumes
                 type: list
@@ -291,6 +301,7 @@ def run_module():
         snapshot_lvm_verify_only=dict(type="bool"),
         snapshot_lvm_mount_origin=dict(type="bool"),
         snapshot_lvm_bootable=dict(type="bool"),
+        snapshot_lvm_revertable=dict(type="bool"),
         snapshot_lvm_mountpoint_create=dict(type="bool"),
         snapshot_lvm_unmount_all=dict(type="bool"),
         snapshot_lvm_percent_space_required=dict(type="str"),
@@ -306,6 +317,7 @@ def run_module():
             options=dict(
                 name=dict(type="str"),
                 bootable=dict(type="bool"),
+                revertable=dict(type="bool"),
                 volumes=dict(
                     type="list",
                     elements="dict",