Add button to hide card description

This commit adds a button to each card that allows the user to show/hide the card description. The description is shown by default.

src/gjb-kanban/src/components/card/KanbanCard.css

+.triangle-down {
+    width: 0;
+    height: 0;
+    border-left: 0.25em solid transparent;
+    border-right: 0.25em solid transparent;
+    border-top: 0.5em solid #fff;
+}
+
+.triangle-right {
+    width: 0;
+    height: 0;
+    border-top: 0.25em solid transparent;
+    border-bottom: 0.25em solid transparent;
+    border-left: 0.5em solid #fff;
+}
+
 .kanbanCardBody {
     border-bottom-left-radius: 0.75em;
     border-bottom-right-radius: 0.75em;
     text-align: left;
     padding: 0.5em 1em 0.5em 1em;
     background-color: beige;
-
 }
 
 .kanbanCardHeader{
@@ -22,6 +37,11 @@
     padding: 0.5em;
 }
 
+.alone {
+    border-bottom-left-radius: 0.75em;
+    border-bottom-right-radius: 0.75em;
+}
+
 #card-Priority{
     border: solid black;
 }
@@ -30,4 +50,4 @@
     text-align: left;
     background-color: white;
     color: white;
-}
\ No newline at end of file
+}