FdoSecrets: UI improvements

- Use proper model for database and session in settings page
- Fix button text (unlock/lock) not changed according to the database locking status
- Fix button icons not present on icon themes other than Breeze
- Fix the disconnect button may got clipped when new session opens

share/icons/application/scalable/actions/object-locked.svg

@@ -0,0 +1,14 @@
+<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24">
+  <defs id="defs3051">
+    <style type="text/css" id="current-color-scheme">
+      .ColorScheme-Text {
+        color:#232629;
+      }
+      </style>
+  </defs>
+ <path style="fill:currentColor;fill-opacity:1;stroke:none" 
+     d="M 11,3 C 8.784,3 7,4.784 7,7 l 0,4 -2,0 c 0,2.666667 0,5.333333 0,8 4,0 8,0 12,0 l 0,-8 c -0.666667,0 -1.333333,0 -2,0 L 15,7 C 15,4.784 13.216,3 11,3 m 0,1 c 1.662,0 3,1.561 3,3.5 L 14,11 8,11 8,7.5 C 8,5.561 9.338,4 11,4"
+     class="ColorScheme-Text"
+       transform="translate(1,1)"
+     />
+</svg>

share/icons/application/scalable/actions/object-unlocked.svg

@@ -0,0 +1,15 @@
+<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24">
+  <defs id="defs3051">
+    <style type="text/css" id="current-color-scheme">
+      .ColorScheme-Text {
+        color:#232629;
+      }
+      </style>
+  </defs>
+ <path 
+    style="fill:currentColor;fill-opacity:1;stroke:none" 
+   d="m11 3c-2.216 0-4 1.784-4 4v1h1v-.5c0-1.939 1.338-3.5 3-3.5 1.662 0 3 1.561 3 3.5v3.5h-5-1-1-1-1v1 7h1 10 1v-8h-1-1v-4c0-2.216-1.784-4-4-4m-5 9h10v6h-10v-6"
+    class="ColorScheme-Text"
+     transform="translate(1,1)"
+    />
+</svg>