[VyOS] Project April 2023 update

Overview of improvements made to v1.4 SAGITTA (next LTS release):

Support for the Babel routing protocol was added. See documentation for details on how to set it up.
FRR version was upgraded to v8.5. See below for the new BGP options this update brings.
The containerization module podman now uses the netavark network stack. Benefits include better IPv6 support, improved performance and improved support for containers attached to multiple networks. Although `netavark' doesn't natively support VRF, container networks can be assigned to VRF networks on VyOS.
VyOS now uses chrony rather than the old NTPd for its NTP implementation, which allows for machine-readable NTP op mode output and more future improvements.