bitcast fixes
* ValidationState_t and idUsage now store the addressing model and memory model of the SPIR-V module (this is necessary for certain instructions that need different checks depending on if the logical or physical addressing model is used)
* removed SpvOpPtrAccessChain and SpvOpInBoundsPtrAccessChain from spvOpcodeIsPointer again as these are disallowed in logical addressing mode and only allowed in physical addressing mode (which doesn't use/need spvOpcodeIsPointer in the first place)
* added SpvOpImageTexelPointer and SpvOpCopyObject to spvOpcodeIsPointer
* OpLoad/OpStore now only check if the used pointer operand originated from a valid pointer producing opcode in logical addressing mode (as per 2.16.1)
* moved bitcast pointer tests to the kernel / physical addressing model part (+cleanup)
* renamed spvOpcodeIsPointer to spvOpcodeReturnsLogicalPointer to clarify this function is only meant to be used with the logical addressing model