Move JSObfu to a gem pull it into the Rex namespace.

Moves JSObfu out to its own repo/gem, with a bunch of new specs/fixes/features. External interface remains the same.

##### Verification

- [ ] ie_setmousecapture_uaf - pass
- [ ] ie_cgenericelement_uaf - pass
- [ ] ie_cubtton_uaf - pass
- [ ] ms13_069_caret - pass
- [ ] ms13_055_canchor - pass
- [ ] ms14_012_textrange – pass