bitcast fixes

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