Improve the external approver view in Approval Path by ensuring that all content elements are properly displayed for external approvers.

For Jira issue and Confluence page.

Edit: After big changes introduced to issue html renderer and guarana adf (for example concurrency was added to the issue renderer, so I removed it from my solution), approach to this task and implementation had to be redefined and it needs second round of review and testing.
Under this task I also realized

APFJ-496: Introduce MediaController for external approver viewWithdrawn

In the meantime I had to also migrate from using deprecated endpoints for Confluence.

For issue rendering I use parametrized issue-html-renderer with custom layout, styling and attachments/media support and preview, for page rendering I created new page html renderer based on the issue renderer and moved it to separate package so other apps can use it too.

For testing:

Check XSS vulnerabilities.
Verify few different pages, different Jira issues etc.

Supported elements:

Confluence page:
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Jira issue:
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