[MCPE-178372] Double slabs were flattened incorrectly

“double_wooden_slab” block is now split into unique instances “double_oak_slab”, “double_spruce_slab”, “double_birch_slab”, “double_jungle_slab”, “double_acacia_slab”, “double_dark_oak_slab”

This change from the 1.20.70.20 beta doesn't match how Java handles these blocks, leading to disparity, unlike most of the flattening changes. In Java, double slabs are a block state of the normal slab blocks.

How to reproduce

/setblock ~ ~ ~ oak_slab[type=double]

Expected result
Double oak slab is placed

Observed result
Syntax error

List from ~~MCPE-178379~~:

Block	Double ID	Single ID (to merge into)
Oak Slab	`oak_double_slab`	`oak_slab`
Spruce Slab	`spruce_double_slab`	`spruce_slab`
Birch Slab	`birch_double_slab`	`birch_slab`
Jungle Slab	`jungle_double_slab`	`jungle_slab`
Acacia Slab	`acacia_double_slab`	`acacia_slab`
Dark Oak Slab	`dark_oak_double_slab`	`dark_oak_slab`
Mangrove Slab	`mangrove_double_slab`	`mangrove_slab`
Cherry Slab	`cherry_double_slab`	`cherry_slab`
Bamboo Slab	`bamboo_double_slab`	`bamboo_slab`
Bamboo Mosaic Slab	`bamboo_mosaic_double_slab`	`bamboo_mosaic_slab`
Crimson Slab	`crimson_double_slab`	`crimson_slab`
Warped Slab	`warped_double_slab`	`warped_slab`
Cobbled Deepslate Slab	`cobbled_deepslate_double_slab`	`cobbled_deepslate_slab`
Polished Deepslate Slab	`polished_deepslate_double_slab`	`polished_deepslate_slab`
Deepslate Brick Slab	`deepslate_brick_double_slab`	`deepslate_brick_slab`
Deepslate Tile Slab	`deepslate_tile_double_slab`	`deepslate_tile_slab`
Tuff Slab	`tuff_double_slab`	`tuff_slab`
Polished Tuff Slab	`polished_tuff_double_slab`	`polished_tuff_slab`
Tuff Brick Slab	`tuff_brick_double_slab`	`tuff_brick_slab`
Mud Brick Slab	`mud_brick_double_slab`	`mud_brick_slab`
Blackstone Slab	`blackstone_double_slab`	`blackstone_slab`
Polished Blackstone Slab	`polished_blackstone_double_slab`	`polished_blackstone_slab`
Polished Blackstone Brick Slab	`polished_blackstone_brick_double_slab`	`polished_blackstone_brick_slab`
Cut Copper Slab	`double_cut_copper_slab`	`cut_copper_slab`
Exposed Cut Copper Slab	`exposed_double_cut_copper_slab`	`exposed_cut_copper_slab`
Weathered Cut Copper Slab	`weathered_double_cut_copper_slab`	`weathered_cut_copper_slab`
Oxidized Cut Copper Slab	`oxidized_double_cut_copper_slab`	`oxidized_cut_copper_slab`
Waxed Cut Copper Slab	`waxed_double_cut_copper_slab`	`waxed_cut_copper_slab`
Waxed Exposed Cut Copper Slab	`waxed_exposed_double_cut_copper_slab`	`waxed_exposed_cut_copper_slab`
Waxed Weathered Cut Copper Slab	`waxed_weathered_double_cut_copper_slab`	`waxed_weathered_cut_copper_slab`
Waxed Oxidized Cut Copper Slab	`waxed_oxidized_double_cut_copper_slab`	`waxed_oxidized_cut_copper_slab`