[Feature] Update Syntax for Querying Group By Items

### Is this your first time submitting a feature request?

- [X] I have read the [expectations for open source contributors](https://docs.getdbt.com/docs/contributing/oss-expectations)
- [X] I have searched the existing issues, and I could not find an existing issue for this feature
- [X] I am requesting a straightforward extension of existing metricflow functionality, rather than a Big Idea better suited to a discussion

### Describe the feature

Currently, the CLI follows a dundered syntax for specifying dimensions e.g. `booking__paid_at__month`. Instead, this syntax should be updated to follow the syntax for the `WhereFilter`. e.g. `TimeDimension('booking__paid_at', 'month')`

### Describe alternatives you've considered

_No response_

### Who will this benefit?

_No response_

### Are you interested in contributing this feature?

_No response_

### Anything else?

_No response_