[WIP] Add support for dynamic match policy changes and always use first match for feasibility/satisfiability

[milroy]

This PR adds support for dynamically changing the match policy based on a jobspec or other conditions. It also configures the first match policy to be used for satisfiability/feasibility checks to improve performance.

~This PR addresses but likely does not completely solve the satisfiability/feasibility check performance problem reported in issue #1159.~ (The system configuration at the time would not have benefited from this change.