audio: copier: Refactor deep copy of copier config

[wjablon1]

Code for copying copier_data is ambiguous. A comment suggests that the deep copy (data structure + variable-length array) is not needed but the copy of variable-length array is performed afterwards. This change rectifies this by placing ipc4_copier_module_cfg at the end of copier_data structure as it contains a variable-length array. This enables single memory allocation and single, clean 1:1 copy for the complete copier_data with the variable-length addition.