tools/contrib: add assign_crimson_cores as a more general replacement for balance_cpu

Improvements:
- shorter
- has tests
- uses lscpu -e --json to get logical<->physical mappings and avoid
  needing to parse cpu ranges in lscpu --json
- supports allocating alienstore threads
- supports requiring physical cores only independently for alienstore
  and seastar reactors

Signed-off-by: Samuel Just <[email protected]>

Author: athanatos