Allow fractional vote weights

[rbennettcw]

Link to Issue

Closes: #10832

Description of Changes

• Fixes vote weight to allow fractional values
  • Backend still uses non-decimal wei representation of balance as source of truth
  • Frontend converts integer wei to human-readable decimal format for rendering
• Adds migration to multiply existing calculated vote weights (originally, the value was truncated so that only full tokens counted, e.g. 10^18 == 1 token –– now we store the full wei representation for both voting power and calculated voting weight)

Test Plan

• Create ETH native topic
  • Go to topic discussions page, confirm that balance is shown in decimal format
• Create ERC20 topic
  • Go to topic discussions page, confirm that balance is shown in decimal format
• For both, make a contest and vote on a thread– confirm that vote weight renders correctly

Deployment Plan

N/A

Other Considerations

N/A