Add flagging reasons to block list entries.

[marklindhout]

Every entry can have multiple reasons for being added to the block list. These reasons need to be attached to the domain’s or URL’s entry in the block list for clarity and display to the user.

A suggestion was provided about how to implement this for list entries. This could look like the following:

const domains = {
  "domain-a.tld": [
    {
      reason: "antisemitism",
      proof: "https://...",
      added: 1598085593878
    }
  ],
  "domain-b.tld": [
    {
      reason: "racism",
      proof: "https://...",
      added: 1598085593878
    },
    {
      reason: "opinion_presented_as_truth",
      proof: "https://...",
      added: 1598085587587
    }
  ]
}

From which the extension could then form presentable strings with i18n methods via the messages.json file, as in the following example:

browser.i18n.getMessage('blockReason_' + domains['domain-a.tld'][0].reason)

and the following value in src/i18n/en/messages.json, for example:

"blockReason_opinion_presented_as_truth": {
  "message": "Opinions or beliefs are being presented as proven truth.",
  "description": "Block reason, according to rule 6: Opinions or beliefs are being presented as proven truth."
},