Merge PR #61937 into wip-vshankar-testing-20250311.100342-debug

Merge PR #61937 into wip-vshankar-testing-20250311.100342-debug

* refs/pull/61937/head:
	add debug
	test/libcephfs: include inode type change test for snapdiff
	mds: include deleted file dentry in snapdiff readdir result
	cephfs-mirror: integrate blockdiff API for regular file transfers
	cephfs-mirror: current sync mschanism uses sync mechanism subclass'ing
	cephfs-mirror: switch to remote dir_root when local prev snapshot is unavailable
	qa: add test for syncing already existing snapshots
	cephfs_mirror: avoid latest changes on the source fs to enable mirroring
	test: add file blockdiff tests
	libcephfs / client: wire up file blockdiff
	mds: add blockdiff operation support
	tools/rados: include latest snapshot sequence in listsnaps