Merge branch '17562-filter-issues-is-only-visible-when-user-is-logged-in' into 'master'

#17562 Fixes issues list filter only visible when user is logged in

## What does this MR do?

1. Moves the issue/MR list search form out of the `if current_user` conditional, allowing guests to view the field.

2.  Adds some margin to the search form, this is because in mobile view for guest users, the field was not supported by the RSS button and the New Issue button and would drop to meet the list.

## Are there points in the code the reviewer needs to double check?

Are there any views where the `margin-bottom: 12px` will affect the styling?

## Why was this MR needed?

Guest user UX. Nothing feels better than increasing intangible value!

## What are the relevant issue numbers?

Fixes #17562.

## Screenshots (if relevant)

![Screen_Shot_2016-05-16_at_23.48.06](/uploads/cf0f0c48287517ac3e83b204b4ee09b2/Screen_Shot_2016-05-16_at_23.48.06.png)

/cc @jschatz1 

**UPDATE:**

![Screen_Shot_2016-05-20_at_16.13.22](/uploads/eb854838a514d0d54d0f13bde1636b8a/Screen_Shot_2016-05-20_at_16.13.22.png)

See merge request !4171

CHANGELOG

@@ -179,6 +179,7 @@ v 8.8.0
   - Fixed advice on invalid permissions on upload path !2948 (Ludovic Perrine)
   - Allows MR authors to have the source branch removed when merging the MR. !2801 (Jeroen Jacobs)
   - When creating a .gitignore file a dropdown with templates will be provided
+  - Shows the issue/MR list search/filter form and corrects the mobile styling for guest users. #17562
 
 v 8.7.7
   - Fix import by `Any Git URL` broken if the URL contains a space

app/assets/stylesheets/framework/nav.scss

@@ -171,6 +171,7 @@
     > form {
       display: inline-block;
       margin-top: -1px;
+      margin-bottom: 12px;
     }
 
     .icon-label {
@@ -207,7 +208,7 @@
 
     @media (max-width: $screen-xs-max) {
       padding-bottom: 0;
-
+      width: 100%;
       .btn, form, .dropdown, .dropdown-menu-toggle, .form-control {
         margin: 0 0 10px;
         display: block;
@@ -238,16 +239,6 @@
         margin: 0;
       }
     }
-
-    /* Small devices (tablets, 768px and lower) */
-    @media (max-width: $screen-sm-max) {
-      width: 100%;
-      text-align: left;
-
-      input {
-        width: 300px;
-      }
-    }
   }
 }