[SPIR-V] The order of instructions leads to errors in pointer element type deduction or crashes compilation

[michalpaszkowski]

The current implementation of SPIRVEmitIntrinsics sometimes allows generating duplicate spv_assign_ptr_type and spv_assign_type intrinsics.

In these cases the order of instructions (and which intrinsic is selected first) plays a role in correct type deduction. In other words, the order of instructions or operands sometimes leads to incorrect type deduction or compilation crashes.

TODO: Add a simple test case