consolidate `env` command's arguments and flags

### Is this feature request related to a new or existing Amplify category?

New category

### Is this related to another service?

_No response_

### Describe the feature you'd like to request

As shown in the [documentation](https://docs.amplify.aws/cli/teams/commands/#commands-overview), `env` commands use either `--name`, `--envName`, or take environment name as an argument (e.g. `env checkout`). This is requesting a consolidation of these decisions in favor of a unified experience.

### Describe the solution you'd like

n/a

### Describe alternatives you've considered

n/a

### Additional context

_No response_

### Is this something that you'd be interested in working on?

- [ ] 👋 I may be able to implement this feature request

### Would this feature include a breaking change?

- [x] ⚠️ This feature might incur a breaking change