Add TASK_ERROR to CHANGELOG for 0.22.0

Review: https://reviews.apache.org/r/27930
Added module loading to scheduler driver.

Review: https://reviews.apache.org/r/27806
Integrated CRAM-MD5 Test Authenticatee module into scheduler.

Review: https://reviews.apache.org/r/27812
Updated upgrades.md and CHANGELOG for changes on AuthenticationStartMessage.

Review: https://reviews.apache.org/r/27675