[Bug]: No deserialization failure when using mcp.custom-tool with `table/view` entity

### What happened?

DAB is expected to fail in deserialization if we use the entity `mcp.custom-tool: true` property for an entity that is not from stored-procedures. Currently there is no failure if we use the command `dab start` and we use the property mentioned above in a `table/view` entity.

### Version

2.0.0-rc

### What database are you using?

Azure SQL

### What hosting model are you using?

_No response_

### Which API approach are you accessing DAB through?

_No response_

### Relevant log output

```Text

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### Code of Conduct

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