Support relative paths for custom set paths for KhronosTextureContainer2

[Steffen-T]

Can't use relative paths for KhronosTextureContainer2.URLConfig. Only absolute paths work.
Forum discussion suggests a simple Tools.GetAbsoluteUrl is missing.
Perhaps this is also needed for MeshoptCompression.Configuration.

Desktop

• OS: Windows 10
• Browser: Chrome
• Version: 106.0.5249.119

[sebavan]

@bghgary feel free to reassign if needed ?

[bghgary]

MeshoptCompression already supports relative urls: https://github.com/bghgary/Babylon.js/blob/c599fb01de51ab3eba031c8d1d3c609351e8aa23/packages/dev/core/src/Meshes/Compression/meshoptCompression.ts#L81