[FR] Selection previews & modifications

Similar to https://www.youtube.com/watch?v=zHZLvJgpRag&t=178s and https://github.com/Brennian/Arceon/wiki/Asset-Placer, it would be nice to implement previews when placing assets (this includes clipboards).

Additionally selection/placing position modification (resizing, rotation) would be a lit feature. This could be done in two ways:
- [ ] Control point selection & moving it around (like [BlingEdit](https://www.reddit.com/r/BlingEdit))
- [ ] Scroll wheel to move a face into the facing direction like seen in [Litematica](https://www.curseforge.com/minecraft/mc-mods/litematica)

The visualization for mods that do this (or [BlingEdit](https://www.reddit.com/r/BlingEdit)) often includes structure block alike bounding box outlines/frames & grabbing points along the edges, in the corners and the middle of a face.

Assets should also have an automatic rotation mode like in [Arceon](https://www.youtube.com/watch?v=JhbEYIhG2UM)

Experiments to implement these features have already been done:
- Outlines: [the structure block branch](https://github.com/thebigsmileXD/MagicWE2/tree/mcstructure-schematic-structurenbt) / [the asset branch](https://github.com/thebigsmileXD/MagicWE2/tree/assets). libstructure is currently in a state where it focuses on data format / vanilla implementation. For this feature to actually work, these things must be done:
- - [x] Spawn the structure block & blockentity either at the corner of the selection or outside the FOV
- - [x] Implement an easier way to quickly update the bounding box
- - [x] ~~If the tile gets out of render distance, respawn it somewhere else~~
- Previews of structures: [Tweet](https://twitter.com/XenialDan/status/1341913532284207105) [Minecarts](https://www.youtube.com/watch?v=Iv2xxzQBh0w) [Falling Blocks](https://www.youtube.com/watch?v=zACn4QQyU4M). These actually performed really well. Falling blocks would be the best performing one. Sadly, one shows the block without meta values (always meta 0), and the other always shows the hand model. Due to this, both options do not show the actual blockstate.

**Related issues and pull requests**
#225 #221 #187 https://github.com/thebigsmileXD/MagicWE2/issues/21