### Why I did it
Currently there is only rsyslog plugin support for /var/log/syslog, meaning we do not detect events that occur in frr logs such as BGP Hold Timer Expiry that appears in frr/bgpd.log.
##### Work item tracking
- Microsoft ADO **(number only)**: 13366345
#### How I did it
Add omprog action to frr/bgpd.log and frr/zebra.log. Add appropriate regex for both events.
#### How to verify it
sonic-mgmt test case
#### Why I did it
Improve naming convention for bgp notification events and change type of leaf for sonic-events-host mem usage from uint64 to decimal64
#### How I did it
Replace "-" with "_"
Replace uint64 with decimal64
#### How to verify it
Run yang model unit tests
#### Description for the changelog
Change YANG model leaf naming convention for bgp notification
With this PR in, you flap BGP and use events_tool to see the published events.
With telemetry PR #111 in and corresponding submodule update done in buildimage, one could run gnmi_cli to capture BGP flap events.
