[Fix] Mitigate XSS attack vector by cleaning input before it hits our Database (#171)

## Changes

- All text input fields are now cleaned with nh3 to remove html tags. We allow certain html tags under `settings.py/ALLOWED_HTML_TAGS` so we can easily update the tags we allow in the future.
- All names and descriptions now use the template tag `nh_safe` in all html files.
- Usernames and emails are a small exception and are not allowed any html tags

Co-authored-by: Liam Brydon <62733830+MyCreativityOutlet@users.noreply.github.com>
Co-authored-by: jebus <lorsbach@envipath.com>
Co-authored-by: Tim Lorsbach <tim@lorsba.ch>
Reviewed-on: enviPath/enviPy#171
Reviewed-by: jebus <lorsbach@envipath.com>
Co-authored-by: liambrydon <lbry121@aucklanduni.ac.nz>
Co-committed-by: liambrydon <lbry121@aucklanduni.ac.nz>

templates/modals/objects/generic_set_external_reference_modal.html

@@ -1,3 +1,4 @@
+
 {% load static %}
 <!-- Delete Object -->
 <div id="generic_set_external_reference_modal" class="modal" tabindex="-1">
@@ -23,7 +24,7 @@
                             {% if entity == object_type %}
                                 {% for db in databases %}
                                     <option id="db-select-{{ db.database.pk }}" data-input-placeholder="{{ db.placeholder }}"
-                                            value="{{ db.database.id }}">{{ db.database.name }}</option>`
+                                            value="{{ db.database.id }}">{{ db.database.name|safe }}</option>`
                                 {% endfor %}
                             {% endif %}
                         {% endfor %}