fix(security): Prevent XSS with warning messages (`addWarningMsg()`) (refs #4838)

Also:
- Prevent XSS with action done message (`addActionDone()`)
- Prevent XSS with error message (`exitError()`)
- Add `cleanhtmljs()` function in `freedom_util.php`
fix(security): Prevent XSS in viewcard.php (refs #4844)
Merge pull request #1194 from eguaj/3.2-A4838

fix(security): Prevent XSS (closes #4838)(closes #4844)