Tweaks to extensions processing in janus-pp-rec

Added some NULL checks to postprocessor

Initialize and destroy mutexes and conditions to be consistent with the rest of the codebase (#3608)

Add trailing LF to debug trace (#3620)

Fix build error when using older OpenSSL API (#3623)

Fixed typo in SIP plugin docs

Fixed typo in Janus docs

Bumped to version 1.4.1

Updated Changelog (1.4.0)

Fix for SIP plugin not offering SRTP in response to offerless INVITEs (#3618)

Add RTP forwarders support to SIP and NoSIP plugins (#3583)

Allow Devices test demo to auto-select first available devices

Fixed inconsistencies when parsing SDP video profiles

Updated year in demos and docs

Lay foundations for plugin-specific unique session ID in SIP and NoSIP plugins (#3607)