feat(sync): boilerplate for sync-v1.1 protocol

[jansegre]

This is a complimentary PR to #581

The reasoning is to create a barrier between peers using the new sync code. The protocol and implementation are backwards compatible, but a barrier helps ensure that peers that are only running sync-v1.1 (not the bridge peer running both versions) will almost certainly (unless someone is intentionally spoofing the sync version) connect to other peers running sync-v1.1, and that should be of great help to #581

Acceptance Criteria

• add a new sync-v1.1 version marker that will use the same class as sync-v1.0 (which was just sync-v1 before)
• disable sync-v1.0 by default, requiring the use of a cli param to enable it
• enable sync-v1.1 whenever sync-v1.0 would be enabled before
• builder will keep referencing a single sync-v1 version, which will only enable sync-v1.1 and not sync-v1.0, this is because the class used is exactly the same and there's no need to make the tests aware of this difference

[codecov]

Codecov Report

Merging #583 (c1eaae7) into master (38bdb64) will decrease coverage by 0.01%.
The diff coverage is 95.65%.

@@            Coverage Diff             @@
##           master     #583      +/-   ##
==========================================
- Coverage   83.47%   83.46%   -0.01%     
==========================================
  Files         221      222       +1     
  Lines       19144    19163      +19     
  Branches     2623     2625       +2     
==========================================
+ Hits        15981    15995      +14     
- Misses       2587     2589       +2     
- Partials      576      579       +3     

Impacted Files	Coverage Δ
hathor/p2p/manager.py	67.54% <75.00%> (+0.32%)	⬆️
hathor/builder/builder.py	91.06% <100.00%> (ø)
hathor/builder/cli_builder.py	79.04% <100.00%> (+0.07%)	⬆️
hathor/manager.py	70.97% <100.00%> (ø)
hathor/p2p/sync_v1_1_factory.py	100.00% <100.00%> (ø)
hathor/p2p/sync_version.py	78.94% <100.00%> (-8.56%)	⬇️

... and 2 files with indirect coverage changes