R1:2d0e7c37e1f5

Rename "IMPORTED_CLOSEABLE" to "IMPORTED_PERMANENT" to clarify the meaning of the flag

Summary:
Ref T13591. This is an old flag with an old name, and there's an import bug because the outdated concept of "closable" is confusing two different behaviors.

This flag should mean only "is this commit reachable from a permanent ref?". Rename it to "IMPORTED_PERMANENT" to make that more clear.

Rename the "Unpublished" query to "Permanent" to make that more clear, as well.

Test Plan:
- Grepped for all…