Petrifried oak slab isn't included in #non_flammable_wood and #wooden_slabs

Petrified oak slabs are wooden slabs that don't burn, to be more precise, they look like oak slabs, but act like stone ones.

Despite that, they're not included the #non_flammable_wood item tag, nor the #wooden_slabs block/item tag. They are included in #slabs block/item tag though.

As a result, commands and/or data packs that use those tags will not find petrified oak slabs, while it is expected they do. This was also the cause for MC-176597, but that no longer applies due to its removal from the creative inventory.

Fix steps:

• add minecraft:petrified_oak_slab as an entry to #non_flammable_wood item tag.
• add minecraft:petrified_oak_slab as an entry to #wooden_slabs item and block tags.
• remove minecraft:petrified_oak_slab from #slabs item and block tags, as #wooden_slabs is included in it (or they would be in the tag twice).