Update PSUseCorrectCasing to enforce correct case for an enum

[xtqqczze]

Expected behavior

Get-ChildItem nosuchitem -ErrorAction SilentlyContinue

Actual behavior

Get-ChildItem nosuchitem -ErrorAction silentlycontinue

[bergmeister]

At the moment the rule corrects:

• Cmdlet name casing (when first introduced in 1.18.3)
• Cmdlet parameter name casing starting with 1.19.0

Therefore this could be the next logical progression although maybe not quite as easy as it looks at first.