[cudapoa] consolidate macros for banded alignment in single header

[tijyojwad]

Right now the macros for banded alignment like CUDAPOA_BANDED_MATRIX_RIGHT_PADDING are not shared between the kernel code and other sources that determine sizes for bands (such as in batch.cu). For now they're hard coded to specific numbers, but this is error prone. This needs to be fixed to the macros are shared between files.