EXRLoader: Introduces output-format API

[sciecode]

Closes #31429, #31493.

Description

Introduces setExpandedFormat loader configuration to control whether the output should be converted to RGBAFormat automatically. Defaults to true.

/cc @mrdoob

[sciecode]

Updated PR according to feedback, now supports setOutputFormat() and defaults to RGBAFormat.
Accepts RedFormat, RGFormat and RGBAFormat.

RGBFormat is currently treated as invalid, cause it used to be emulated in Mozilla Firefox, which led to horrible performance. But I can extend support if it's not longer the case.

I also took the opportunity to support format compression (e.g RGBAFormat -> RedFormat), which was trivially done.

[mrdoob]

Excellent!