Handle moving cloned enemies

Resolves #842. #### Checklist - [x] I have read the [coding conventions](https://github.com/LostArtefacts/TR-Rando/blob/master/CONTRIBUTING.md#coding-conventions) - [x] I have read the [testing guidelines](https://github.com/LostArtefacts/TR-Rando/blob/master/CONTRIBUTING.md#testing-guidelines) - [x] I have added a changelog entry about what my pull request accomplishes, or it is an internal change #### Description If environment mods flood a room and subsequently move an enemy by index, this ensures any clones are also moved. Refactored quite a bit and added some tests. Also fixes some trigger positions in GW in the above scenario where Lara could potentially start beyond the enemy triggers.