Merge pull request #4425 from microsoft/mikebattista/#4423

Update /_utils/Set-All-Text-File-Template-Encodings.ps1 to support PowerShell Core

_utils/Set-All-Text-File-Template-Encodings.ps1

@@ -8,6 +8,14 @@
 # Any files that don't have the desired encoding will be changed
 #  so they are encoded as desired.
 
+if ($PSVersionTable.PSEdition -eq "Desktop") {
+    Write-Host "The latest version of PowerShell is required to run this script. Windows PowerShell is not supported."
+    Write-Host ""
+    Write-Host "Install the latest stable release of PowerShell from https://aka.ms/powershell-release?tag=stable."
+
+    return;
+}
+
 function Is-EncodedCorrectly
 {
    [OutputType([Boolean])]
@@ -17,7 +25,7 @@ function Is-EncodedCorrectly
      [string]$Path
    )
 
-   [byte[]]$byte = get-content -Encoding byte -ReadCount 3 -TotalCount 3 -Path $Path
+   [byte[]]$byte = Get-Content -AsByteStream -Raw -Path $Path
 
    # EF BB BF (UTF8 + BOM)
    if ( $byte[0] -eq 0xef -and $byte[1] -eq 0xbb -and $byte[2] -eq 0xbf )