feat: Pass extension to test-exclude, use TestExclude.globSync.

[coreyfarrell]

BREAKING CHANGE: The logic involving include/exclude processing has
changed. Results should be verified to ensure all desired sources have
coverage data.

[coreyfarrell]

The testing changes are less significant than it looks. The tests were actually checking for results that were impossible in practice. Although shouldInstrument('file-without-extension') could previously return true, the file would never have been instrumented because it has no extension for the require hook.

[coveralls]

Coverage increased (+0.1%) to 93.898% when pulling 651eced on coreyfarrell:updated-test-exclude into d8f28e9 on istanbuljs:master.

[coveralls]

Coverage increased (+0.1%) to 93.898% when pulling 651eced on coreyfarrell:updated-test-exclude into d8f28e9 on istanbuljs:master.

[coveralls]

Coverage increased (+0.1%) to 93.898% when pulling 651eced on coreyfarrell:updated-test-exclude into d8f28e9 on istanbuljs:master.

[coveralls]

Coverage increased (+0.1%) to 93.898% when pulling 651eced on coreyfarrell:updated-test-exclude into d8f28e9 on istanbuljs:master.