Prior to this change, the `ConvertFrom-Json` cmdlet returnedd a
**Hashtable** object when used with the **AsHashtable** parameter.
Starting with PowerShell 7.3, it instead returns an **OrderedHashtable**
object.

This change:

- Modifies the output type and parameter documentation to reflect the
  updated object type for 7.3.
- Updates the parameter documentation for 7.0+ to better reflect the
  reasons to use the **AsHashtable** parameter.
- Resolves #9039
- Fixes AB#4440