Support Epoch Extensions in HotStuff Committee

[jordanschalm]

This PR updates the Consensus Committee to support epoch extensions. Addresses #5730.

Changes

• Modifies protocol.Epoch FinalView method to account for any extensions.
• Modifies committees.Consensus to handle EpochExtended protocol event. When we observe an epoch extension, we simply re-compute the leader selection for the entire epoch, including the new view range added by the extension. This is slightly wasteful, incurring a cost of around 20-30ms per extension on Mainnet, but simplifies the business logic and state quite a bit compared to tracking each extension independently.
• Moves internal event processing to a shared channel Now that we can move into and out of EFM several times over the lifecycle of the component, it is easier to reason about correctness if we use a shared channel for events to enforce in-order processing. The event consumer function prepares a (potentially blocking) event handler function to be executed and passes the closure into the channel. The worker goroutine pulls event handler closures off the channel and executes them in order.

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 61.15702% with 47 lines in your changes missing coverage. Please review.

Project coverage is 41.70%. Comparing base (9c3ed48) to head (43754d1).

Files	Patch %	Lines
...nsensus/hotstuff/committees/consensus_committee.go	74.39%	16 Missing and 5 partials :warning:
consensus/hotstuff/committees/leader/consensus.go	0.00%	13 Missing :warning:
state/protocol/inmem/epoch.go	31.25%	10 Missing and 1 partial :warning:
state/protocol/badger/snapshot.go	77.77%	2 Missing :warning:

Additional details and impacted files

@@                   Coverage Diff                    @@
##           feature/efm-recovery    #6154      +/-   ##
========================================================
+ Coverage                 41.68%   41.70%   +0.01%     
========================================================
  Files                      1975     1975              
  Lines                    139306   139258      -48     
========================================================
- Hits                      58072    58071       -1     
+ Misses                    75182    75139      -43     
+ Partials                   6052     6048       -4     

Flag	Coverage Δ
unittests	41.70% <61.15%> (+0.01%)	:arrow_up:

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