New Rule Suggestion: Validate ps1xml Schema

*.Format.ps1xml and *.Types.ps1xml have a XSD now. This can be used to create a rule to validate types and format XML schema.

In my build scripts I have the following code to validate ps1xml files.

$ps1xmlFiles = Get-ChildItem -Path $modulePath -Filter *.ps1xml

foreach ($ps1xml in $ps1xmlFiles) {
    [xml]$xml = Get-Content -Path $ps1xml.FullName
    $null = $xml.Schemas.Add($null, 'https://raw.githubusercontent.com/PowerShell/PowerShell/master/src/Schemas/Format.xsd')
    $null = $xml.Schemas.Add($null, 'https://raw.githubusercontent.com/PowerShell/PowerShell/master/src/Schemas/Types.xsd')
    $xml.Validate( { throw "File '$($ps1xml.Name)' schema error: $($_.Message)" })
}

Start with the proposed PowerShell validation snippet and the referenced Format.xsd and Types.xsd schemas. Review how PSScriptAnalyzer rules discover and report issues, then confirm the rule handles both *.Format.ps1xml and *.Types.ps1xml files and reports schema errors; add or run relevant rule tests if available.