Auto-generate PowerShell completion file

[CHIKAMATSU Naohiro]

The gup command generates shell completion files for bash, zsh, and fish.
However, gup does not generate shell completion file for PowerShell.

I do not have Windows, so this task has a very low priority.
I would be happy to have this feature implemented for Windows users!!
There is a function (GenPowerShellCompletionFile()) that generates a shell completion file for PowerShell, so it can be implemented if you know where to generate the file.

gup/internal/completion/completion.go

Lines 17 to 26 in 195e47b

 // DeployShellCompletionFileIfNeeded creates the shell completion file. 
 // If the file with the same contents already exists, it is not created. 
 func DeployShellCompletionFileIfNeeded(cmd *cobra.Command) { 
 	if !isWindows() { 
 		makeBashCompletionFileIfNeeded(cmd) 
 		makeFishCompletionFileIfNeeded(cmd) 
 		makeZshCompletionFileIfNeeded(cmd) 
 	} 
 }