[the-glu]

This PR shows a few possible optimizations for raft.

It should be split into dedicated PRs when parent PRs are merged, to be compatible with the latest version of the code.

Optimizations are:

• Proposals encoded with a simple encoder
• Optional compression of proposals above a specific threshold
• Smaller encoding of known ovn formats
• Removal of extra information in upsertOperationalIntentReference, moving cells computation into transaction + removing useless keys

This greatly improves performance with latency (around 10x with flightsinsub and 33ms of latency).

[MariemBaccari]

Optimizations 1 and 2 are addressed by #1765 and #1766 (using protobuf is simpler and only adds a few bytes to binary encoding).
The 4th optimization was partially addressed by PRs that define custom payloads and partially outdated since we have decided to precompute the cells coverage and include them in the payload instead of the raw 4d volume.

NB: I will update my comment when optimization 3 is addressed and this PR can be closed.