craftassist folder refactor

## Type of Issue

Select the type of issue:
- [ ] Bug report (to report a bug)
- [ ] Feature request (to request an additional feature)
- [x] Tracker (I am just using this as a tracker)
- [x] Refactor request
- [ ] Documentation Ask

## Checklist

Just did a quick pass over the current folder structure and following things stick out and we should discuss :

- [x] craftassist/sentry folder can be deleted
- [x] craftassist/render_vision_dataset/ can be deleted
- [x] minecraft_render -> delete
- [x] visual_segmentation -> delete
- [x] render_schematic -> delete
- [x] render_one_block_change -> delete
- [x] bin/ -> low_level
- [x] client/ -> low_level
- [x] logging/ -> low_level
- [x] schematic_convert -> deleted and updated Makefile and README docs that mentioned it
- [x] schematic_convert.py -> delete
- [x] config_parser.py -> lowlevel
- [x] cuberite_process.py -> lowlevel
- [x] edit_cuberite_config.py -> lowlevel
- [x] FAQ for MAC -> lowlevel
- [x] Makefile -> lowlevel
- [x] ping_cuberite -> lowlevel
- [x] place_blocks -> lowlevel
- [x] README -> lowlevel
- [x] repo.py -> lowlevel
- [x] requirements.txt ?
- [x] wait_for_cuberite -> lowlevel
- [x] servermgr move to new folder called `tools` (fix dependencies in files inside after)
- [x] server -> low_level
- [x] Lots of cuberite files can be combined / in one folder under low_level - lets do this as a follow up to this cleanup.
- [x] crowdsourcing folder can go in tools.
```
droidlet:
tools
crowdsourcing
servermgr
```
- [ ] we can separate out `tools` folder from `scripts` folder in root