Load additional Bandcamp comments

[fynngodau]

Follow-up to #586 and #620.

Currently, we are only loading the first batch of comments (max. 3).

Example of an album where multiple pages of comments are available: https://alfamist.bandcamp.com/album/bring-backs

[SuperSonicHub1]

The request Bandcamp makes after loading more comments looks like this: https://alfamist.bandcamp.com/api/tralbumcollectors/2/reviews. I presume alfamist can be replaced with any artist slug. It's a POST request that sends form data.

{
  "tralbum_type": "a",
  "tralbum_id": 87634066,
  "token": "1:1615548668:6888782:1:1:0",
  "count": 7,
  "exclude_fan_ids": []
}

For tralbum_type, I assume a is for "album", and that t might be for "track." The initial token parameter, which acts as a cursor, can be fount in the JSON blob at div#collectors-data[data-blob] of the initial HTML document at root['reviews'][5]['token'].

The request returns JSON that has the same shape as what can be found in the HTML doc, so everyone should be familiar with it already.

I've attached an HTTP Archive to this comment detailing an anonymous browser session to the page linked in OP which simply loads the page and clicks the more... button. You can view it using Google's HAR Analyzer or Jan Odvarko's HTTP Archive Viewer.

alfamist.bandcamp.com_redacted.har.txt