Test-Json should have a -JsonFile parameter

## Summary of the new feature/enhancement
The currently documented Test-Json command has parameters:
```
-Json
-Schema
```
Recently added was:
`-SchemaFile`

To create an orthogonal view, the following parameter should be supported.
`-JsonFile`

Aliases would also be helpful.
```
-JsonString for -Json
-SchemaString for -Schema
```