Community: parse reply count and polls

[ChunkyProgrammer]

This PR parses the reply count for community posts
and parses the poll type for community posts (including an optional image)

Poll:

{
    type: "poll",
    totalVotes: number,
    choices: [
      {
         text: string
         image?: [
             {
               url: string,
               width: number,
               height: number
             }
         ]
      }
    ]
}

[SamantazFox]

Code looks good. I've made some recommendations below

[SamantazFox]

Tested on https://test.invidious.io -> works fine!

[SamantazFox]

Thanks for your PR :)