Bug 27942: Prevent XSS vulnerabilities in quote-upload

Bug 27942: Prevent XSS vulnerabilities in quote-upload

When uploading new quotes the JS variables are not escaped correctly.

Test plan:
Create a new file with the following content (remove the first and last lines containing """):
"""
":this is a source","this is a text"
"this is another ❤one","and another text❤"
"this <script>alert('foo');</script>","and <script>alert('❤');</script>"
"""

Go to Home › Tools › Quote editor
Click Import quote
Select the file
Edit the third line, hit enter
Import quotes

Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
Signed-off-by: Julian Maurice <julian.maurice@biblibre.com>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>