Update text for unknown operations in proposals

[abitmore]

General

PR for #3661.

Show the text "Unknown operation" with the operation type number for operations which are not yet implemented in UI. For those operations, link to the internal block explorer is removed because it is either broken (on the proposal details page) or redundant (on the account activities page).

Translation was done with Google Translate.

See https://pr.bts.mobi/#/account/blockchain-prize for result of changes.

This is the first step in fixing issues like #3661. Since it is a catch-all solution, it could reduce similar scam issues in the future. I think it's urgent and we need to release a new version containing it ASAP. To be clear, I know we want to support showing all operation types in proposals, and we can do it step by step.

General

Please make sure the following is done:

• Pull request is onto develop
• If you haven't already, have a look at
  • https://github.com/bitshares/bitshares-ui/blob/develop/CODE_OF_CONDUCT.md
  • https://github.com/bitshares/bitshares-ui/blob/develop/CONTRIBUTING.md

Code Preparation

Please review all your changes one last time before committing

• Check for unused code
• No unrelated changes are included
• None of the changed files are reformatting only
• Code is self explanatory or documented
• All written text is properly translated (english language)

Testing

The branch has been tested on the following browsers (desktop and mobile view)

• Chrome
• Opera
• Firefox
• Safari

Please provide screenshots/licecap of your changes below

In German:

[sschiessl-bcp]

For reference, this is how it looks before