docs(js): Add Astro snippet for filter integration (#13035)

Author: angelikatyborska

platform-includes/configuration/filter-application-key/javascript.astro.mdx

@@ -0,0 +1,13 @@
+```js {tabTitle:Vite} {filename:astro.config.mjs} {6}
+export default defineConfig({
+  integrations: [
+    sentry({
+      sourceMapsUploadOptions: {
+        unstable_sentryVitePluginOptions: {
+          applicationKey: "your-custom-application-key",
+        },
+      },
+    }),
+  ],
+});
+```

platform-includes/configuration/filter-application-key/javascript.sveltekit.mdx

@@ -1,6 +1,6 @@
 ```js {tabTitle:Vite} {filename:vite.config.js} {6}
 export default defineConfig({
-	plugins: [
+  plugins: [
     sentrySvelteKit({
       sourceMapsUploadOptions: {
         unstable_sentryVitePluginOptions: {