fix(progress-indicator): allow currentIndex to be programmatically updated

docs/src/pages/framed/ProgressIndicator/ProgrammaticProgressIndicator.svelte

@@ -0,0 +1,52 @@
+<script>
+  import {
+    ProgressIndicator,
+    ProgressStep,
+    Button,
+  } from "carbon-components-svelte";
+
+  let currentIndex = 1;
+  let thirdStepComplete = false;
+</script>
+
+<ProgressIndicator bind:currentIndex>
+  <ProgressStep
+    complete
+    label="Step 1"
+    description="The progress indicator will listen for clicks on the steps"
+  />
+  <ProgressStep
+    complete
+    label="Step 2"
+    description="The progress indicator will listen for clicks on the steps"
+  />
+  <ProgressStep
+    complete="{thirdStepComplete}"
+    label="Step 3"
+    description="The progress indicator will listen for clicks on the steps"
+  />
+  <ProgressStep
+    label="Step 4"
+    description="The progress indicator will listen for clicks on the steps"
+  />
+</ProgressIndicator>
+
+<div style="margin: var(--cds-layout-02) 0">
+  <Button
+    on:click="{() => {
+      currentIndex = 2;
+    }}"
+  >
+    Set index to 2
+  </Button>
+  <Button
+    kind="ghost"
+    on:click="{() => {
+      thirdStepComplete = !thirdStepComplete;
+    }}"
+  >
+    Toggle step 3
+  </Button>
+</div>
+
+<h3>Current index: {currentIndex}</h3>