🥕[Bug]: `dab update --relationship.fields` does not support compound keys.

### What happened?

When using `dab update` with `--relationship.fields` you cannot pass multiple keys.

## Input

`dab update Fake --config "c:\Temp\delme-demo-jerry\dab-config-copy.json" --relationship Series_Character --target.entity Series_Character --cardinality one --relationship.fields "SeriesId:SeriesId,CharacterId:CharacterId"`

### Output

```text
C:\Temp\delme-demo-jerry>dab update Fake --config "c:\Temp\delme-demo-jerry\dab-config-copy.json" --relationship Series_Character --target.entity Series_Character --cardinality one --relationship.fields "SeriesId:SeriesId,CharacterId:CharacterId"
Information: Microsoft.DataApiBuilder 1.2.11
Information: User provided config file: c:\Temp\delme-demo-jerry\dab-config-copy.json
Loading config file from c:\Temp\delme-demo-jerry\dab-config-copy.json.
Error: Please provide the --relationship.fields in the correct format using ':' between source and target fields.
Error: Failed to update the Entity: Fake.
Error: Could not update the entity: Fake.
```

## The Problem (relationship fields)

https://github.com/Azure/data-api-builder/blob/main/src/Cli/ConfigGenerator.cs#L1595-L1607

## Compared To (mapping option)

https://github.com/Azure/data-api-builder/blob/main/src/Cli/Utils.cs#L141-L157

### Code of Conduct

- [x] I agree to follow this project's Code of Conduct

Commencez dans src/Cli/ConfigGenerator.cs aux lignes 1595-1607 et comparez son analyse des champs de relation avec src/Cli/Utils.cs aux lignes 141-157. Exécutez la commande dab update fournie avec les deux paires de champs ; c’est terminé lorsque les champs source et cible composés sont acceptés sans l’erreur de format.

Rédigé par le modèle d'indexation à partir du texte de l'issue.