Fixes#4882 and updates GitHub certificate fingerprint to the current one
in BearSSL_Validation example.
When setting a authentication mode or stopping, clear all others out in case
the object is being re-used.
Add in a yield during the SSL handshake to allow a graceful timeout and not
a WDT error when the remote server hiccups. Thanks to @Jeroen88 for
finding and testing this.