GODRIVER-1844 export unified test runner

[iwysiu]

All of the functions that were not calling the runner were made private. Notes:

1. matches_test.go got broken up into its functions and its test
2. Some of the variables in EntityMap were renamed to avoid collisions between the variables and the now unexported functions.

[divjotarora]

@iwysiu There's a number of test failures in the linked patch build. Can you look into those before we review?

[iwysiu]

@iwysiu There's a number of test failures in the linked patch build. Can you look into those before we review?

Should be fixed! As a note, I suspect that there will be further changes for the atlas planned maintenance stuff, but I figured this was a big enough change to get looked at on its own.

[benjirewis]

LGTM! Just to clarify, we do want to export integration/unified/unified_spec_test and not integration/unified_spec_test, right?

[divjotarora]

Can you explain how the planned maintenance test runner provides test files to run? Does it give you one filepath at a time, a path to a directory of files, or something else?

[iwysiu]

Can you explain how the planned maintenance test runner provides test files to run? Does it give you one filepath at a time, a path to a directory of files, or something else?

The test runner guide says "json blob" but it looks to me like the ruby implementation reads a file