Allow creating budgets step by step

We introduce the first step (creating the budget).

Co-Authored-By: decabeza <alberto@decabeza.es>

app/assets/stylesheets/admin/budgets_wizard/creation_timeline.scss

@@ -0,0 +1,34 @@
+.creation-timeline {
+  display: flex;
+  list-style-type: none;
+  margin: $line-height * 2 0;
+  position: relative;
+
+  li {
+    border-top: 4px solid $admin-border-color;
+    display: inline-block;
+    font-size: $small-font-size;
+    font-weight: bold;
+    padding: $line-height / 2 $line-height * 3 0;
+    text-transform: uppercase;
+
+    &::before {
+      background: $admin-border-color;
+      border-radius: 50%;
+      content: "";
+      height: 20px;
+      margin-left: $line-height / 2;
+      position: absolute;
+      top: -8px;
+      width: 20px;
+    }
+
+    &[aria-current] {
+      border-color: $brand;
+
+      &::before {
+        background: $brand;
+      }
+    }
+  }
+}