Use h tag for widget title instead of b tag (#12504)

* Change b tag to h3 tag

* Remove margin

* Update snapshots

test/components/views/elements/__snapshots__/AppTile-test.tsx.snap

@@ -125,9 +125,9 @@ exports[`AppTile for a pinned widget should render 1`] = `
               width="20px"
             />
           </span>
-          <b>
+          <h3>
             Example 1
-          </b>
+          </h3>
           <span />
         </span>
       </span>
@@ -211,9 +211,9 @@ exports[`AppTile for a pinned widget should render permission request 1`] = `
               width="20px"
             />
           </span>
-          <b>
+          <h3>
             Example 1
-          </b>
+          </h3>
           <span />
         </span>
       </span>
@@ -364,9 +364,9 @@ exports[`AppTile preserves non-persisted widget on container move 1`] = `
                     width="20px"
                   />
                 </span>
-                <b>
+                <h3>
                   Example 1
-                </b>
+                </h3>
                 <span />
               </span>
             </span>