Add Eye Graph Preset to HDRP Shader List

[johnpars]

Purpose of this PR

This PR copies the Eye ShaderGraph preset in the HDRP Test Projects, and places it into HDRP Resources.
This makes it available to users as a quick starting point for creating eye materials.
Note that we have accompanying documentation for this on the way, in #2424

---

Testing status

Locally, I have created a new material, switched the shader to HDRP/Eye in the shader list, and quickly authored an eye to test for parity with eye materials in the original Graphics Tests.

---

Comments to reviewers

• Currently, there is no Eye sample in the HDRP Material Sample. Do we want one for 10.2?
• Would it make sense to update the graphics tests to point to this graph in HDRP Resources?
• Slightly depends on a small change in Changed the names of some of the parameters for the Eye Utils SG Nodes. #2413, which renames some util nodes inputs. I have used the eye graph from that PR branch, so that when this merges it will update automatically (tested locally).

[remi-chapelain]

Approving the PR since the graph is known and used in some DXR and HDRP Test ! ✔️
YES, I think it would be a great addition to our material sample to have this and/or multiple version of this as I already stated when the HDRP test have been made ! :)
The same way we have our material sample for hair / decals / fabric, we certainly need one with Eye especially how hard it is to setup it and have a proper result ! And all the sample in the HDRP/DXR test looks great and can be integrated a wide range of use.

As for linking the HDRP test with this one, My two cents, is I don't think it's a good idea since any slight modification on this graph would make the test fail and need to rebuild the capture. I think the test graph and the sample graph should remain different.