Option to specify differernt provider version than the bound version

[magodo]

The tool is bound to a specific azurerm provider version (the latest version in most of the time). This is fine for exporting to a new workspace. Whilst for appending to an existing workspace, the user might pinned the provider to a different version. In this case, the tool should be able to identify that version and use the same version. Meanwhile, it would be nice if users can specify different provider as they wish. The problem is that tfadd is bound to a specific provider version, in order to create a valid terraform config. Using a different provider version might break this.