Nostalgia Shader v4.0 Preview E2

Oi,

there have been a bunch of changes since the last version, and as NostalgiaVX is now on Tier 2 I thought that it'd make sense to make the previews of the regular Nostalgia Shader available for all tiers for now :)

Changelog:

- adjusted tonemap response
- removed unintentional purkinje effect
- fixed exposure bug on hitches and lags
- fixed block selection box in 1.17
- added mappings for 1.17 emitters
- reworked emission behaviour
- added support for the nether
- added ggx tail clamping for reduced rough reflections noise and fireflies
- added POM settings