Enable rendering with unbounded far distance

[Flarkk]

This PR allows rendering with unlimited camera zfar - or rather limited by the sole floating point range i.e. ~3.4e+38 in single precision.

This effectively untaps the potential of reverse-z depth buffer with single precision build, in all 3 renderers Forward+, Mobile and Compatibility. XR is not covered though (see notes below).

Outline

Currently zfar cannot be pushed further than barely ~1e6 times znear because of numerical precision limitations with some methods of struct Projection.
With the default znear = 0.05 this sets the maximum view distance to ~50 km.
While it's enough in most cases, it can be a hard limitation for open worlds, space games, and any very large scene.
Beyond this limit, scene rendering currently breaks and Godot starts spaming errors.

This PR removes this limitation with 3 key changes :

• Stores the 6 frustum planes alongside the projection matrix in the rendering server's internals. Both are equivalent representations except that the former allows retrieving near/far distances and boundary points with much more accurate numerical precision
• Restricts the use of the matrix representation to the sole cases where projections / un-projections are performed. Use the 6 planes in any other situation (typically to retrieve znear / zfar, get boundary points, etc...)
• Bundles the 6 planes representation into a new struct Frustum with a few helper methods for convenience. This avoids relying of Vector<Plane> everywhere and improves readability

This PR is in a good enough state to get first reviews. There are still a few details to be ironed out though :

• The sky seems to mask some (but not all) far away objects - only in Compatibility and Mobile
• Objects farther than 1e20 disappear when Occlusion culling is on

Demo : full-scale scene

large_zfar.zip

Vegetation is ~1m tall and ~10m from the observer
The terrain is 10 km large
The moon's radius is 1,700 km and is 400,000 km from the observer
The Andromeda galaxy is 152,000 light-years wide and is 2.5 million light years from the observer

Performance

This PR improves very slightly the frame process time of an empty scene by ~ 0.5%.
This is likely due to the significant number of planes retrieval operations avoided by the fact the 6 planes are already made available.

Before	After

Notes

• XR is left unchanged for now because this would require the XR APIs to return frustum planes in addition to the projection matrix. This may be the subject of another PR
• I spent a considerable amount of time making sure all effects work with large zfar. Some require additional PRs to be merged.
  Test project for effects : effects.zip (make sure to preview the large znear camera in each scene)

Effects	Works with large zfar	Issue
Bokeh DOF	✔️ with #99755
SSR	✔️ with #99693
SSIL	✔️
SSAO	✔️
Sky	✔️	Sometimes hides far away objects in Compatibility and Mobile ?
Shadows	✔️
SDFGI	❌	Crash with zfar or znear > ~1e+20 : #99967
SSS	✔️ with #99755
Fog	✔️

• Add tests for Camera3D frustum functions #99961 and Add tests for Viewport's camera override functions #99962 help ensuring non-regression on Viewport and Camera3D

Closes godotengine/godot-proposals#10515
Closes #55070
Supersedes #95944

[Flarkk]

Rebased and fixed style issues to allow CI to run.

[Flarkk]

Rebased on top of #99974