Refactors McastHandler to optimize network failures

Changes:
- Introduces a paths store
- Optimizes SINKS_ADDED, SINKS_REMOVED
- Uses SINKS_REMOVED to handle egress failures
- Optimizes SOURCES_ADDED, SOURCES_REMOVED
- Leverages SOURCES_REMOVED to handle ingress failures
- Optimizes infra failures

Change-Id: I16d264f58d6fe11cfce4a546f7b4ab82a9fcc21b
4 files changed
tree: 1b16bf04c2ecbe722258e3df12d1059b299cadc7
  1. BUILD
  2. app/
  3. web/