M2C and Sentries can be set up in tents

### Testmerges

N/A

### Round ID

N/A

### Description of the bug

As Titled.
You can put something like an M2C, presumably the M56D and sentries in tents to hide them from xenos

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

They should respect the same blockers that stop cades from being there probably.

### How do we reproduce this bug?

1. Set up tent
2. Put down an M2C
3. And/Or drag a sentry in and anchor it
...

### 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)

Reproduce the issue by placing a tent, deploying an M2C, and anchoring or dragging in a sentry; also check the presumed M56D case. Compare these placements with the blockers that prevent cades from being placed, and consider the issue complete when these deployables can no longer be set up inside tents while valid placements still work.

Written by the indexing model from the issue text.