Workflow improvements for eliminating EOL usage and addressing CVEs

[MichaelSimons]

This Epic tracks the work to improve the process for eliminating usage of EOL images and to address image CVEs.

• Eliminate noise from vulnerability report - Add lifecycle annotations to images pushed to MCR docker-tools#1201
• Notification mechanism for vulnerabilities - https://github.com/dotnet/dotnet-docker-internal/issues/5717
• https://github.com/dotnet/dotnet-docker-internal/issues/5712
• Define owner(s) for each Dockerfile #1148
• Document process for unblocking builds / maintaining this repo #972
• Docker EOL - Notifying cusomters when the Docker container OS reaches EOL dnceng#2543
• Add last run information in Docker End-of-Life report dnceng#2559
• Docker EOL - Report on usage of EOL annotated images dnceng#3615