Integrate divergences between cherry-picked implementation and manual work in #9620

[sergio-mena]

This issue tracks the progress in integrating the divergences detected between the vote extension implementation in branch feature/abci++vef (backported from v0.36.x and #9620 (which was done manually)

Some of the divergences have turned out to be quite involved so I will be submitting several PRs to keep separation of concerns.

• Easy ones / Obvious bugs: Divergences in comparison with #9620. Part 1: easy/obvious #9888
• Refactor MakeVote and signAddVote: Divergences in comparison with #9620. Part 2: Improved checks for vote extension signing in the unit tests #9895
• Handling of vote extension activation in the blocksync reactor (and possibly the bug Anoma hit this summer) Divergences in comparison with #9620. Part 3: Fix problems found in blocksync reactor #9926
• Other/remaining Divergences in comparison with #9620. Part 4: Other changes spotted #9927

[sergio-mena]

Closed by #9988, #9895, #9926, #9927