### Godot version

3.5 (991bb6ac7) -> 4.0.beta10 (d0398f62f)

### System information

Windows 11

### Issue description

I have some relatively simple tilesets created in version 3.5 containing textures, collision shapes, and occlusion polygons. These tilesets are almost completely unusable when migrated into Godot 4 without recreating most of the tileset by hand. Specifically:

- Tile size seems to always be set at 16x16 (this might be the root cause of some of the other issues). This might not be easy to convert properly since tile size is a property of the TileMap in Godot 3, but of the TileSet in Godot 4. That being said, the converter could likely guess at the proper tile size based on the tiles present in the map (e.g. given that all my tiles are 32x32, it would be logical to set tile size as 32x32).
- No occlusion layer is created, meaning **all occlusion polygons are lost**.
- Collision polygons are incorrectly offset from the textures: ![image](https://user-images.githubusercontent.com/4420888/210156434-90331901-5e1c-4f16-9839-19a21bbcc5d9.png) (this wouldn't be as big of a deal if there was a way to "drag" entire collision polygons rather than just individual vertices, but it seems like to only way to fix them is to recreate them from scratch).
- Collision polygons aren't rotated properly in auto-generated rotation alt tiles:
![image](https://user-images.githubusercontent.com/4420888/210156473-069cc7c4-3466-4aba-83ff-693dbba31737.png)
- (I imagine these same issues are present for tileset navigation layers, but I haven't tested that)

Probably related to issues #64006 and #67218.

### Steps to reproduce

- Create a basic tileset with occlusion + collision polygons in Godot 3.
- Convert the project to a Godot 4 project.
- Open the project in 4 and pay attention to the Tileset's textures & collision/occlusion polygons.


### Minimal reproduction project

[convert4.zip](https://github.com/godotengine/godot/files/10328029/convert4.zip)

public:
	
	void set_tile_set(const TileSet *p_tile_set);
	void notify_tile_data_properties_should_change();
	void add_occlusion_layer(int p_index);
	void move_occlusion_layer(int p_from_index, int p_to_pos);
	void remove_occlusion_layer(int p_index);
	void add_physics_layer(int p_index);
	void move_physics_layer(int p_from_index, int p_to_pos);
	void remove_physics_layer(int p_index);
	void add_terrain_set(int p_index);
	void move_terrain_set(int p_from_index, int p_to_pos);
	void remove_terrain_set(int p_index);
	void add_terrain(int p_terrain_set, int p_index);
	void move_terrain(int p_terrain_set, int p_from_index, int p_to_pos);
	void remove_terrain(int p_terrain_set, int p_index);
	void add_navigation_layer(int p_index);
	void move_navigation_layer(int p_from_index, int p_to_pos);
	void remove_navigation_layer(int p_index);
	void add_custom_data_layer(int p_index);
	void move_custom_data_layer(int p_from_index, int p_to_pos);
	void remove_custom_data_layer(int p_index);
	void set_allow_transform(bool p_allow_transform);
	bool is_allowing_transform() const;
	
	TileData *duplicate();
	
	void set_flip_h(bool p_flip_h);
	bool get_flip_h() const;
	void set_flip_v(bool p_flip_v);