feat(dev): autofill login starturl setting (#4918)

New dev setting to autofill the start url:

```
"aws.dev.autofillStartUrl": "<url>"
```

Should probably be integrated into the login page for all users somehow, but that requires some UX thought. Here is a quick fix for devs.

Author: hayemaxi

packages/core/src/login/webview/vue/backend.ts

@@ -30,6 +30,7 @@ import { telemetry } from '../../../shared/telemetry'
 import { AuthSources } from '../util'
 import { AuthEnabledFeatures, AuthError, AuthFlowState, AuthUiClick, TelemetryMetadata, userCancelled } from './types'
 import { AuthUtil } from '../../../codewhisperer/util/authUtil'
+import { DevSettings } from '../../../shared/settings'
 
 export abstract class CommonAuthWebview extends VueWebview {
     private metricMetadata: TelemetryMetadata = {}
@@ -291,4 +292,8 @@ export abstract class CommonAuthWebview extends VueWebview {
 
         return authEnabledFeatures.join(',')
     }
+
+    getDefaultStartUrl() {
+        return DevSettings.instance.get('autofillStartUrl', '')
+    }
 }

packages/core/src/login/webview/vue/login.vue

@@ -330,6 +330,7 @@ export default defineComponent({
         }
     },
     async created() {
+        this.startUrl = await this.getDefaultStartUrl()
         await this.emitUpdate('created')
     },
 
@@ -500,6 +501,9 @@ export default defineComponent({
 
             this.$forceUpdate()
         },
+        async getDefaultStartUrl() {
+            return await client.getDefaultStartUrl()
+        },
     },
 })
 </script>

packages/core/src/shared/settings.ts

@@ -729,6 +729,7 @@ const devSettings = {
     ssoCacheDirectory: String,
     enableIamPolicyChecksFeature: Boolean,
     pkceAuth: Boolean,
+    autofillStartUrl: String,
 }
 type ResolvedDevSettings = FromDescriptor<typeof devSettings>
 type AwsDevSetting = keyof ResolvedDevSettings