dependency updates, refactoring, es6

[msimerson]

• authn: replace async.detect with local fn
• aliases: replace async with Promise.all
• dep(async): removed
• dep(ldapjs): update from 1.0.2 to 2.3.3
• noop: remove useless returns
• es6: more arrow functions
• style: inline use of plugin
• ci: switch travis -> GHA
• ci: enable codeql
• test: use RFC example.com for test domain
• test: refactored some to improve error messages
• test: add fixtures for setting up slapd on macosx and linux
• doc(README): update with GHA badge

Test Failure

There's a test failure thats a bit difficult to track down. It manifests when the entire test suite is run and doesn't when a single test file is run. I'm not sure if the concurrency / race condition is within this module or ldapjs but I've no more time to track it down.