Exhaustive switch case with returns can mark a finally block as unreachable

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### 🔎 Search Terms

finally switch exhaustive unreachable

### 🕗 Version & Regression Information

This is the behavior in every version I tried ( doesn't typecheck pre 3.7 ), and I reviewed the FAQ for entries about unreachable code

### ⏯ Playground Link

https://www.typescriptlang.org/play/?#code/MYewdgzgLgBAhjAvDAFANwFwwIwwD4wBMAlEgHwwDeAUDDFAE4CeVtdMEA7gJZTAAWqNKRrt2wOBACmOLAylQArgzAw0bMROlE5C5avViAvmyMwAZtzBwANjZajx4CCBtSAdDZABzFAHIpAA9eP2JTahNqUEhYACMkISwwRQBbWKkGUkQKR0YHDQ4ePkF0EQK6LRlsXSUVNXKYABMpczhFGyga-XrjUwsrW3tWTWdXDy9fAOCoUPDI6OgYYAT0LFwCEnJh+mZtui5eASEysQrJKq66w1PKnRh5WoMCkzozS2s7fLFuc1RGRSkJxuozcnh8-iCITCvVeEWoUWcsEaK0wMGSaQyWRybDye0KhxKwjxZ201XueiuDWarXanXJjx67BeMDeA0+eJ+fwYAKBI0gYzBk0hM2hTLmQA

### 💻 Code

```ts
const c = (v: 1 | 2) => {
try {
switch (v) {
case 1: return v
case 2: return v
}
} finally {
if (true) {
console.log('exit')
}
}
}
```

### 🙁 Actual behavior

The contents of the `finally` blocked are marked as unreachable

### 🙂 Expected behavior

That they are reachable

### Additional information about the issue

While the example seems to include some confusing additions the replication apparently requires:
- The cases to be exhaustive
- No default case
- For the switch expression be typed as a literal union of some form
- An `if` statement to be in the `finally` block

I assume this is a chaotic mix of unreachable patterns upsetting flow analysis. I've also noticed that it you add an unreachable `return` statement after the `switch` then the contents of `finally` become reachable.

Inizia con la riproduzione collegata in TypeScript Playground e confronta lo switch esaustivo su una literal union all’interno di try/finally con le variazioni elencate: un default case oppure un return irraggiungibile dopo lo switch. Traccia l’analisi del flusso che contrassegna l’istruzione if in finally come irraggiungibile, quindi aggiungi una copertura che mostri che il contenuto di finally è raggiungibile e verifica i diagnostics previsti.

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