powershell: escape variable with curly brackets

This fixes an issue with program names that include a dot, in our case
`podman.exe`. This was caused by the change in commit 6ba7ebb.

Fixes #1853

Signed-off-by: Paul Holzinger <pholzing@redhat.com>

powershell_completions.go

@@ -47,7 +47,7 @@ filter __%[1]s_escapeStringWithSpecialChars {
 `+"    $_ -replace '\\s|#|@|\\$|;|,|''|\\{|\\}|\\(|\\)|\"|`|\\||<|>|&','`$&'"+`
 }
 
-[scriptblock]$__%[2]sCompleterBlock = {
+[scriptblock]${__%[2]sCompleterBlock} = {
     param(
             $WordToComplete,
             $CommandAst,
@@ -279,7 +279,7 @@ filter __%[1]s_escapeStringWithSpecialChars {
     }
 }
 
-Register-ArgumentCompleter -CommandName '%[1]s' -ScriptBlock $__%[2]sCompleterBlock
+Register-ArgumentCompleter -CommandName '%[1]s' -ScriptBlock ${__%[2]sCompleterBlock}
 `, name, nameForVar, compCmd,
 		ShellCompDirectiveError, ShellCompDirectiveNoSpace, ShellCompDirectiveNoFileComp,
 		ShellCompDirectiveFilterFileExt, ShellCompDirectiveFilterDirs, ShellCompDirectiveKeepOrder, activeHelpEnvVar(name)))