**Motivation**
[[ https://phabricator.wikimedia.org/T165492 | User testimony, search data ]], and some current wiki behaviors have identified a user need of searching through multiple talk pages at once.
**Task**
Create a check box named "Discussion" that adds (or removes) the namespaces for Project + all talk namespaces to the list of namespaces being searched.
{F13187817}
**Acceptance Criteria**
- when all namespaces associated with the button are included, the checkbox is checked.
- if you click the checkbox in this state, all namespaces associated with this checkbox are removed, the checkbox becomes unchecked
- when some or none (but not all) of the associated namespaces are currently included the checkbox is unchecked
- if you click the checkbox in this state, all namespaces not currently included in the search are included, the checkbox becomes checked.
- when the "all" checkbox is selected, this box is also selected (since the namespaces are also part of all)