Factor out voter decision making from council election

[bedeho]

These should be separate runtime modules.

The concept of having the voters decide on some proposition is fundamental, and currently, it is intertwined with the council election. It's very likely that the voters may need to make decisions on other things, and perhaps even be given direct access to the proposal system, hence we need to factor this out at the module level. We also have a number of possible improvements in the pipeline for how voting should work, and implementing these would also benefit from this cleanup.

The standalone voting module should support having multiple independent votes active at any given time.

[bedeho]

One question in this approach is what we do about the self-voting that council members do? The cleanest may simply be to no longer count the staking as part of the voting, and instead councilors can self-vote through their membership.