allow ejecting from coverage reporting in jest_config_template.mjs

[Aghassi]

This addresses the ability to let users define their own coverage reporting logic in unique cases. For us, we use monocart-coverage-reporter. In doing so, we needed to write our own globalTeardown for jest that uses the split coverage logic, but also manipulates the dat files before they are passed to bazel

[gregmagolan]

SKIP_SETTING_COVERAGE_DIR is a custom env var that you set on your jest_test targets?

Perhaps we expose this as a config attribute such as automatic_coverage_reporting which default to True but can be opted out of if you roll your own in a globalTeardown?

[Aghassi]

Yes because we source our jest_test from a macro that embeds that in env and then give everyone the same baseline jest.config that we provide which has globalTeardown set. I'm fine with a config attribute, but maybe scope it to be rules_jest_automatic_coverage_reporting so it's not so generic it could have other implications