Allow diff context records to be adjusted

[IdlePhysicist]

This commit enables the number context records to be adjusted, allowing for greater readability in some debugging scenarios.

Closes #358

[dsnet]

Hi, thanks for the contribution.

It's a known issue that the reporter does not print enough context for all use cases and this is something worth addressing, but I believe exposing the numContextRecords is too low-level of a implementation detail to expose. We probably want a single higher-level option to control the amount of printout, but it's unclear what that option should exactly be.