smarter compiler output for string literals in expressions

[Rich-Harris]

Describe the problem

In rare cases you might need to put a string literal inside curlies, e.g. to represent a { character itself (yes, you can do it with HTML entities but {'{'} is easier) or for finer control over whitespace:

https://svelte-5-preview.vercel.app/#H4sIAAAAAAAAEyWMsQ6EIBBEf4XsFduQXE9336EWqIuSKBBYLzk3_PtBrGbeS2YEnD-ogBkEgj0JDHxSAg38Sx3Klw6mxiVeeelGXmSXXQ3oYkStcLb5iRsnZYvi3YetjmFkeaoWVNiEvPuwtq8zrt55WsFwvqhO9Q8H_VvBhgAAAA==

This results in unnecessarily complicated output.

Describe the proposed solution

-$.text_effect(node_1, () => `${$.stringify($.unwrap(thing))},${$.stringify(' ')}`);
+$.text_effect(node_1, () => `${$.stringify($.unwrap(thing))}, `);

Alternatives considered

N/A

Importance

nice to have