break expense component into smaller pieces

src/app/components/expense/expense-form/expense-form.component.scss

@@ -0,0 +1,20 @@
+.expense-form-container {
+  display: grid;
+
+  mat-form-field {
+    width: 100%;
+  }
+}
+
+@media (min-width: 550px) {
+  .expense-form-container {
+    grid-template-columns: 1fr 1fr;
+    gap: 1rem;
+  }
+}
+
+@media (min-width: 800px) {
+  .expense-form-container {
+    grid-template-columns: 1fr 1fr 1fr;
+  }
+}