Rule proposal: warn when using constructor for hashtables

[Jaykul]

Creating a hashtable via the constructor without specifying an IEqualityComparer results in using the default IEqualityComparer (which uses Object::Equals), which means that strings are compared in a case-sensitive way. This may be confusing and unexpected to PowerShell scripters who are accustomed to case-insensitive hashtables.

Basically, I think you should warn people if you see:

New-Object System.Collections.Hashtable
[hashtable]::new()

Or any variation on those: (System.Collections.Hashtable = Collections.Hashtable = Hashtable) with or without parameters (unless the parameters include a custom IEqualityComparer).

The warning should recommend creating hashtables with the literal initializer @{} for speed (over New-Object) and case-sensitivity reasons as cited above.

[Jaykul]

As an example, this is the case currently in the PowerShellGet module where Find-Module returns a Microsoft.PowerShell.Commands.PSRepositoryItemInfo object that has a case-sensitive hashtable on it's AdditionalMetadata property (although it has other hashtable properties which are not case-sensitive).