cuda aligner API to take in max available memory and max ref/query sizes

[tijyojwad]

1. each aligner batch to take in max memory and max ref/query sizes and determine how many how alignments can be performed in the batch.
2. provide api to check max alignments possible
3. actual max alignments may me larger based on inputs processed so far, and actual max can be determined by continually adding and checking return value of add alignment api call

[tijyojwad]

Done for banded Myers implementation, but Hirschberg still uses old API that doesn't cap memory from the API itself