Introduces an `idx_count` field to `struct vkd3d_shader_register`. Another patch set is needed for further validations and to use this field where applicable.
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v7: vkd3d-shader/tpf: Validate input and output index ranges for default control point phases.
vkd3d-shader/tpf: Remove an unnecessary carriage return from a parser error message.
vkd3d-shader/tpf: Validate index range declarations.
https://gitlab.winehq.org/wine/vkd3d/-/merge_requests/198