[FEATURE]:Support update with subqueries

### Report hasn't been filed before.

- [x] I have verified that the bug I'm about to report hasn't been filed before.

### What version of `drizzle-orm` are you using?

v0.39.0

### What version of `drizzle-kit` are you using?

0.30.4

### Other packages

_No response_

### Describe the Bug

An update statement can't have subqueries without workarounds.

example:
```typescript
await db
.update(shows)
.set({
availableCount: sql`${db
.select({ count: count() })
.from(entries)}`,
})
```
(note the extra ``sql`${`` before the subquery)

i'd expect to be able to do that:
```typescript
await db
.update(shows)
.set({
availableCount: db
.select({ count: count() })
.from(entries),
})
```

I found this workaround [here](https://www.answeroverflow.com/m/1149994717749190717).