Format editable report elements (column, filters, etc)

Covered by behat tests.

Manual testing instructions

1. Log in as admin
2. Navigate to Plugins > Filters > Manage filters in site administration
3. Set Multi-Language Content to On and Apply to: Content and headings
4. Navigate to Reports > Report builder > Custom reports in site administration
5. Press New report
6. Choose a name and select the Users report source
7. Press Save
8. Rename the User > Full name column to the following:

   <span class="multilang" lang="en">Full name (EN)</span><span class="multilang" lang="de">Full name (DE)</span>

9. Confirm the User > Full name column is now named Full name (EN)
10. Press Settings > Filters
11. Rename the User > Full name filter to the following:

    <span class="multilang" lang="en">Full name filter (EN)</span><span class="multilang" lang="de">Full name filter (DE)</span>

12. Confirm the User > Full name filter is now named Full name filter (EN)
13. Press Preview
14. Confirm the Full name column (the first column) is named Full name (EN)
15. Press Filters
16. Confirm the Full name filter (the first filter) is named Full name filter (EN)