bicepparam typed variables support

**Is your feature request related to a problem? Please describe.**
Currently, with experimental feature typed variables, to use them in bicepparam, I need to use import statement

bicepparam
```bicep
using '../module.bicep'

import * as types from 'module.bicep'

var typedVar { *: types.TType } = {}
```
where module.bicep looks like
```bicep
@export()
type TType { someProp: string? }
```

**Describe the solution you'd like**
I would like to avoid explicit export of type nad using import. the `using` statement should allow me direct, no namespaced access to types declared in referenced bicep file

bicepparam
```bicep
using 'module.bicep'

var typedVar { *: TType } = {}
```
module.bicep
```bicep
type TType { someProp: string? }
```