refactor: replace emoji shortcodes with their unicode equivalent (#4000)

lib/workers/branch/index.js

lib/workers/pr/pr-body-config.js

lib/workers/pr/pr-body.js

lib/workers/repository/onboarding/pr/config-description.js

lib/workers/repository/onboarding/pr/errors-warnings.js

lib/workers/repository/onboarding/pr/index.js

lib/workers/repository/onboarding/pr/pr-list.js

test/workers/pr/__snapshots__/index.spec.js.snap

...boarding/pr/__snapshots__/config-description.spec.js.snap

.../onboarding/pr/__snapshots__/errors-warnings.spec.js.snap

...pository/onboarding/pr/__snapshots__/pr-list.spec.js.snap