Extra level of indentation within #region/#endregion tags

Support indenting an extra level inside regions, both with analyzing and auto-formatting, so it's possible to verify/auto-format code to look like this:

#region
    Get-ChildItem
#endregion

Currently the formatter will do this (because #region/#endregion isn't a token that merits an indent

#region
Get-ChildItem
#endregion

After discussing in the PowerShell slack, I was pointed towards this area where the change would need to be made:
https://github.com/PowerShell/PSScriptAnalyzer/blob/c78f5a60c1f49a5e767286ff6323a2ec0788991a/Rules/UseConsistentIndentation.cs#L146
I believe specifically this would need to be handled in the default part of the switch block.
Per @bergmeister this would most likely get added as a configurable option for the PSUseConsistentIndentation rule.

I'm putting this here because I sort of volunteered to work on it, but it will be a very low priority for me, and also I don't want this information to disappear from the Slack buffer and be gone entirely.

Start in Rules/UseConsistentIndentation.cs at the switch block around the referenced line, especially its default case. Inspect how the PSUseConsistentIndentation rule handles configuration, then define the change so both analysis and auto-formatting can indent code inside #region/#endregion tags. Done means the shown region layout is supported through the intended configurable option.