Allow to set a token limit for a task

### Describe the feature or problem you'd like to solve

Currently each request consumes a certain predicable amount of premium requests - this will change soon and make it completely unpredictable, a task might accidently eat up thwo whole budget for a month.

### Proposed solution

With the upcoming https://github.blog/news-insights/company-news/github-copilot-is-moving-to-usage-based-billing/ it becomes completely unpredictable how much costs a request possibly consumes.

It would therefore be good to set a limit per session / request. If the limit is approached, copilot should ask for confirmation what to do that could be:

1. Complete as soon as possible with what was already accomplished
2. Continue with an increased budget
3. ....

### Example prompts or workflows

_No response_

### Additional context

_No response_

Non sono indicati file, test o punti di ingresso. Inizia individuando la gestione delle richieste di attività e sessione nella CLI, quindi chiarisci come devono funzionare un limite di token e le opzioni di conferma. Il lavoro è completato quando il limite viene applicato a una richiesta o a una sessione e le risposte di budget proposte sono coperte dai test.

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