handle slot name clashes and invalid names

packages/svelte/src/compiler/migrate/index.js

@@ -421,7 +421,7 @@ const template = {
 				slot_props += `...${state.str.original.substring(/** @type {number} */ (attr.expression.start), attr.expression.end)}, `;
 			} else if (attr.type === 'Attribute') {
 				if (attr.name === 'name') {
-					name = /** @type {any} */ (attr.value)[0].data;
+					name = state.scope.generate(/** @type {any} */ (attr.value)[0].data);
 				} else {
 					const value =
 						attr.value !== true

packages/svelte/tests/migrate/samples/slots/input.svelte

@@ -3,3 +3,5 @@
 {#if foo}
 	<slot name="foo" {foo} />
 {/if}
+
+<slot name="dashed-name" />

packages/svelte/tests/migrate/samples/slots/output.svelte

@@ -1,9 +1,11 @@
 <script>
-	let { children, foo } = $props();
+	let { children, foo_1, dashed_name } = $props();
 </script>
 
 <button>{@render children?.()}</button>
 
 {#if foo}
-	{@render foo?.({ foo, })}
-{/if}
+	{@render foo_1?.({ foo, })}
+{/if}
+
+{@render dashed_name?.()}