It is invalid if the same decoration is applied to the same id multiple
times. This adds a check before adding a decoration that the decoration
is not already in the list. If it is, then the duplicate is not added.
Fixes#3627
Apart from allowing redeclaration of gl_MeshPerVertexNV and gl_MeshPerPrimitiveNV blocks, this change also -
- Resize clip/cull perview distances based on static index use
- Error out use of both single-view and per-view builtins
- Add new gtests with redeclared blocks and edit existing test output
- Fix couple of typos
