Type argument with a subset of the parameter constraint's optional keys incorrectly reported as unassignable to constraint

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### 🔎 Search Terms

"does not satisfy the constraint" "keyof" "optional"

### 🕗 Version & Regression Information

- This is the behavior in every version I tried, and I reviewed the FAQ for entries about "constraint"

### ⏯ Playground Link

https://www.typescriptlang.org/play/?#code/C4TwDgpgBAsiAq4IB54BooFUoQB7AgDsATAZygG8oBtAaSgEtCoBrCEAewDMp4BdAPwAuKAFdCLQhwDuzAL4A+KAF4sAbgCwAKG0BjADYBDUuTgBhIydRKK2qFABuh-aIgBCEXESRUGKnUZmNk4eeCgAMihSYAAnJgBzQRFxSRl5BU0tOW0gA

### 💻 Code

```ts
type MyType = U;

class MyClass {
value!: MyType;
}
```

### 🙁 Actual behavior

The following error is reported:

```
Type '{ [K in keyof T & string]?: unknown; }' does not satisfy the constraint '{ [K in keyof T]?: unknown; }'.
Type 'keyof T' is not assignable to type 'keyof T & string'.
Type 'string | number | symbol' is not assignable to type 'keyof T & string'.
Type 'string' is not assignable to type 'keyof T & string'.
Type 'string' is not assignable to type 'keyof T'.
Type 'keyof T' is not assignable to type 'string'.
Type 'string | number | symbol' is not assignable to type 'string'.
Type 'number' is not assignable to type 'string'.
```

### 🙂 Expected behavior

No error should be reported because due to the keys being optional, `{ [K in keyof T & string]?: unknown }` is a subtype of `{ [K in keyof T]?: unknown }` for all `T`.

### Additional information about the issue

_No response_

Riproduci la diagnostica dell’esempio collegato di TypeScript Playground, quindi segui il controllo dei vincoli generici per i tipi mappati con proprietà opzionali e intersected keyof keys. Il lavoro è completato quando l’esempio viene compilato senza errori, mantenendo al contempo il corretto controllo dei vincoli per i casi correlati.

Scritto dal modello di indicizzazione a partire dal testo della issue.