extend FeatureFlags class to include flags' documentation, export for external consumption

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

_No response_

### Is this related to another service?

_No response_

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

Extend the [`FeatureFlags`](https://github.com/aws-amplify/amplify-cli/blob/dev/packages/amplify-cli-core/src/feature-flags/featureFlags.ts#L26) class to include [documentation](https://github.com/aws-amplify/docs/blob/main/src/components/FeatureFlags/feature-flags.json) for each flag. Additionally, export the `FeatureFlags` instance for external consumption (suggestion is as follows)

```tsx
import * as cli from '@aws-amplify/cli-internal'

// get the JSON structure of feature flags
// approach is similar to `Response.json()` https://developer.mozilla.org/en-US/docs/Web/API/Response/json
const featureFlags = await cli.featureFlags.json()

// sample React page to generate FF docs
export function FeatureFlagsPage() {
return (

{featureFlags.map(flag => (

))}

)
}
```

This will remove the need for maintaining this documentation separately, and enables us to automate regenerating the documentation on CLI release.

### Describe the solution you'd like

see above

### Describe alternatives you've considered

n/a

### Additional context

_No response_

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

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

### Would this feature include a breaking change?

- [ ] ⚠️ This feature might incur a breaking change