OPFSPermutedVFS is now deprecated

[rhashimoto]

Can a class provided as an example be deprecated? If yes, then OPFSPermutedVFS is being deprecated. It has been removed from testing and will not be updated.

The new OPFSWriteAheadVFS uses ideas and lessons learned from OPFSPermutedVFS, and is markedly superior in both features and benchmarks.