Free functions for texturing, point clouds, and trace

[curtisblack]

Description

Provides free function API for:

• rs_texture
• rs_texture3d
• rs_environment
• rs_get_texture_info
• rs_get_texture_info_st
• rs_pointcloud_search
• rs_pointcloud_get
• rs_pointcloud_write
• rs_trace

Each of these match the existing signatures of the renderer services equivalents. A new function rs_trace_get is added to retrieve trace results and is intended to replace getmessage("trace", ...) which is currently not available on GPUs.

The fallback for each of these is to call the existing renderer services functions.

To achieve this, the helper structs TextureOpt, TraceOpt, NoiseOpt are removed from the host-only shading context, and are instead added into the LLVM generated code as stack allocations. These allocations only occur if the shader uses these features.

To allow these free functions to compile on GPUs, the texture per-thread context pointer is currently passed null. Future work will be needed to give this a proper home.

To make the pointcloud functions GPU friendly, they had to modified to not use variadic arguments and to avoid dynamic alloca.

Tests

Checklist:

• I have read the contribution guidelines.
• I have updated the documentation, if applicable.
• I have ensured that the change is tested somewhere in the testsuite (adding new test cases if necessary).
• My code follows the prevailing code style of this project. If I haven't
  already run clang-format v17 before submitting, I definitely will look at
  the CI test that runs clang-format and fix anything that it highlights as
  being nonconforming.

[lgritz]

@curtisblack Can you please resolve the merge conflict so we can run the CI?