Add PowerShell herestring autoclosing pairs

[TylerLeonhardt]

fixes #95244

$str = @"
I am a here string
"@

$str = @'
I am also a here string
'@

These @''@ and @""@ should autoclose.

NOTE: PowerShell syntax says that the here string open (@') should be the last characters on a line so we should include a newline in the close.

Proof:

[TylerLeonhardt]

cc @alexdima

[alexdima]

Thank you!