refactor(completion): name path arguments explicitly and share firstArg

The six commands that take a file or directory argument set their
completer directly instead of a Use-line parser wrapping every
command, the first-argument-only wrappers become one firstArg helper,
and only the bash completion help keeps a custom text.

Signed-off-by: bircni <bircni@icloud.com>

internal/app/teams.go

@@ -339,12 +339,7 @@ to set single units instead, or to override some of them.`,
 $ tea team create acme/reviewers --unit repo.code=read,repo.pulls=write
 # give the team access to every repository of the organization
 $ tea team create acme ops --permission admin --all-repositories`,
-		ValidArgsFunction: func(cmd *cobra.Command, args []string, toComplete string) ([]cobra.Completion, cobra.ShellCompDirective) {
-			if len(args) > 0 {
-				return nil, cobra.ShellCompDirectiveNoFileComp
-			}
-			return a.completeOrgs()(cmd, args, toComplete)
-		},
+		ValidArgsFunction: firstArg(a.completeOrgs()),
 		RunE: func(cmd *cobra.Command, args []string) error {
 			org, name, scoped := strings.Cut(args[0], "/")
 			names := 0