fix: wait a tick before collecting form data for validation (#14631)

This way when you're doing
```ts
myForm.fields.foo.set('bar')
myForm.validate();
```
you'll validate on the up-to-date data

closes #14630

Author: dummdidumm

.changeset/kind-emus-run.md

@@ -0,0 +1,5 @@
+---
+'@sveltejs/kit': patch
+---
+
+fix: wait a tick before collecting form data for validation

packages/kit/src/runtime/client/remote-functions/form.svelte.js

@@ -512,13 +512,20 @@ export function form(id) {
 
 					const id = ++validate_id;
 
+					// wait a tick in case the user is calling validate() right after set() which takes time to propagate
+					await tick();
+
 					const form_data = new FormData(element, submitter);
 
 					/** @type {readonly StandardSchemaV1.Issue[]} */
 					let array = [];
 
 					const validated = await preflight_schema?.['~standard'].validate(convert(form_data));
 
+					if (validate_id !== id) {
+						return;
+					}
+
 					if (validated?.issues) {
 						array = validated.issues;
 					} else {