Add alert message component and documentation

- Add custom alert component to simplify the use of custom alerts
- Add documentation for using the custom alert
- Update the login error alert to use the alert component instead of
the Bootstrap-vue component.
- Register alert component in enhanceApp
- Replace Sass variables used in the StatusIcon component style block
to use the Boostrap theme-color and gray Sass functions so the colors
can be used in the Vuepress documentation custom components

Signed-off-by: Derick Montague <derick.montague@ibm.com>
Change-Id: Ibd93402c919a42bd5c24cc9e7c6c8fc6f17a4db4
diff --git a/src/assets/styles/_alerts.scss b/src/assets/styles/_alerts.scss
new file mode 100644
index 0000000..3f103b1
--- /dev/null
+++ b/src/assets/styles/_alerts.scss
@@ -0,0 +1,59 @@
+.alert {
+    display: flex;
+    padding: $spacer;
+    border-width: 0 0 0 3px;
+    color: $gray-800;
+    margin-bottom: $spacer;
+
+    .close {
+      font-weight: 300;
+      opacity: 1;
+    }
+
+    .alert-icon {
+      display: inline-flex;
+      align-items: center;
+      margin-right: $spacer;
+      margin-bottom: $spacer;
+
+      @include media-breakpoint-up(sm) {
+        margin-bottom: 0;
+      }
+    }
+
+    .alert-content {
+      flex: 1 1 auto;
+    }
+
+    .alert-title {
+      margin-bottom: $spacer / 2;
+    }
+
+    .alert-msg {
+      p + p {
+        margin-bottom: $spacer;
+      }
+
+      p:last-of-type {
+        margin-bottom: 0;
+      }
+    }
+
+    &.alert-info {
+      border-left-color: $info;
+      background-color: $info-light;
+      fill: $info;
+    }
+
+    &.alert-danger {
+      border-left-color: $danger;
+      background-color: $danger-light;
+      fill: $danger;
+    }
+
+    &.alert-warning {
+      border-left-color: $warning;
+      background-color: $warning-light;
+      fill: $warning;
+    }
+  }
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