Implement "Delete all messages of a chat"

Fixes #11
3 jobs for 11-delete-all-messages in 3 minutes and 27 seconds (queued for 3 minutes and 22 seconds)
Status Job ID Name Coverage
  Test
passed #6493
pycodestyle

00:01:21

passed #6494
pylint

00:02:06

manual #6495
allowed to fail manual
pytest