bugs for First Person Body Support (#1396)

Created by: yohjimane

All issues below effect branch #1396 and must be completed before we can merge.

1. mixed build errors, can cause first person body to appear floating. The second error occurs on dev branch in mixed builds too.
No longer an issue with new camera positioning method 9dd1ae265d8ff4876a8cc3dfe2c8b1b989d6154a

3. possible to clip through object if facing away from them
No longer an issue new camera positioning method 9dd1ae265d8ff4876a8cc3dfe2c8b1b989d6154a

4. First person body position can "jitter" between original position and corrected position
fixed with 60ac2ea0fcbe1f6ce5700ba705ba015d70b78abd
More info in discord msg

6. First person body syncs at low frame rate in some conditions. I think it depends on whether or not our body can currently cast a shadow. Possibly some performance optimization we need to disable.
fixed with c32e8662b700ca04089d774513ffbc97abcb1c7e
Can be easily reproduced with the settings: r__actor_shadow off and g_first_person_body on
In the video below, I am turning headlamp on, which causes the body to render smoothly. When it is off, the body renders at lower frame rate

7. Actor headlamp is in incorrect position
It needs to be corrected similarly to CWeapon position correction
Would be best if we can find a generic solution that works for CWeapon, CTorch, CCustomDetector etc...
fixed with new camera positioning method 9dd1ae265d8ff4876a8cc3dfe2c8b1b989d6154a

8. IK is incorrectly based on original position
It should be corrected using camera direction similarly to CWeapon position correction.
fixed with new camera positioning method 9dd1ae265d8ff4876a8cc3dfe2c8b1b989d6154a