fix help collision

[ocitrev]

Fix command scoop help when alias help is declared.

When a user has an alias named help, scoop help does not work anymore.
This PR renames the function help to scoop_help to prevent collision with a user alias.

Steps to reproduce:

PS> Set-Alias help Get-Help
PS> scoop help install
help : The term 'local:help' is not recognized as the name of a cmdlet, function, script file, or operable program.
Check the spelling of the name, or if a path was included, verify that the path is correct and try again.
At C:\Users\Eric\scoop\apps\scoop\current\libexec\scoop-help.ps1:16 char:13
+     $help = help $file
+             ~~~~
+ CategoryInfo          : ObjectNotFound: (local:help:String) [], CommandNotFoundException
+ FullyQualifiedErrorId : CommandNotFoundException

Usage: scoop install <app> [options]