Expand templates without parameters

Some templates may not have any parameters or any required parameters particularly if they are built from bicep.

Currently PSRule for Azure will only automatically from CI expands from parameter files. If a template has no parameter file it would not be automatically expanded although could be manually from a PowerShell command line.

We should handle this scenario.

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**Update**: This is already handled for Bicep by configuring expansion options. Issue remains if a template has no required parameters but not parameter file, it isn't currently expanded by any method automatically.