feat(cli): forest-cli f3 powertable get-proportion

[hanabi1224]

Summary of changes

Changes introduced in this pull request:

• implement forest-cli f3 powertable get-proportion

Lotus output:

➜  lotus git:(master) lotus f3 pt gp 1179 1167
{
  "Instance": 43254,
  "FromEC": false,
  "PowerTable": {
    "CID": "bafy2bzacebf32gcvjz7qy65yz634ekyng5hknegnytda7z6wfm5seoaqebbj4",
    "ScaledTotal": 65524
  },
  "ScaledSum": 15,
  "Proportion": 0.0002289237531286246
}

Forest output:

➜  lotus git:(master) forest-cli f3 pt gp 1179 1167
{
  "Instance": 43254,
  "FromEC": false,
  "PowerTable": {
    "CID": "bafy2bzacebf32gcvjz7qy65yz634ekyng5hknegnytda7z6wfm5seoaqebbj4",
    "ScaledTotal": 65524
  },
  "ScaledSum": 15,
  "Proportion": 0.0002289237531286246
}

Reference issue to close (if applicable)

Closes #4994

Other information and links

Change checklist

• I have performed a self-review of my own code,
• I have made corresponding changes to the documentation. All new code adheres to the team's documentation standards,
• I have added tests that prove my fix is effective or that my feature works (if possible),
• I have made sure the CHANGELOG is up-to-date. All user-facing changes should be reflected in this document.