Motion Sensor can be anchored when not on the floor.

### Testmerges

N/A

### Round ID

N/A

### Description of the bug

Title. I.E. A bag.
It shouldn't be anchored in your bag.

### What's the difference with what should have happened?

Not do that

### How do we reproduce this bug?

1. Put one in your bag
2. Anchor it
3.
...

### Issue Bingo

- [x] Issue could be reproduced at least once
- [x] Issue happened in a recent (less than 7 days ago) round
- [x] Couldn't find an existing issue about this (https://github.com/cmss13-devs/cmss13/issues)