Refactor to use urfave/cli/v2 (#25959)

Replace #10912

And there are many new tests to cover the CLI behavior

There were some concerns about the "option order in hook scripts"
(#10912 (comment)),
it's not a problem now. Because the hook script uses `/gitea hook
--config=/app.ini pre-receive` format. The "config" is a global option,
it can appear anywhere.

----

## ⚠️ BREAKING ⚠️

This PR does it best to avoid breaking anything. The major changes are:

* `gitea` itself won't accept web's options: `--install-port` / `--pid`
/ `--port` / `--quiet` / `--verbose` .... They are `web` sub-command's
options.
    * Use `./gitea web --pid ....` instead
* `./gitea` can still run the `web` sub-command as shorthand, with
default options
* The sub-command's options must follow the sub-command
* Before: `./gitea --sub-opt subcmd` might equal to `./gitea subcmd
--sub-opt` (well, might not ...)
    * After: only `./gitea subcmd --sub-opt` could be used
    * The global options like `--config` are not affected

cmd/actions.go

@@ -9,30 +9,31 @@ import (
 	"code.gitea.io/gitea/modules/private"
 	"code.gitea.io/gitea/modules/setting"
 
-	"github.com/urfave/cli"
+	"github.com/urfave/cli/v2"
 )
 
 var (
 	// CmdActions represents the available actions sub-commands.
-	CmdActions = cli.Command{
+	CmdActions = &cli.Command{
 		Name:        "actions",
 		Usage:       "",
 		Description: "Commands for managing Gitea Actions",
-		Subcommands: []cli.Command{
+		Subcommands: []*cli.Command{
 			subcmdActionsGenRunnerToken,
 		},
 	}
 
-	subcmdActionsGenRunnerToken = cli.Command{
+	subcmdActionsGenRunnerToken = &cli.Command{
 		Name:    "generate-runner-token",
 		Usage:   "Generate a new token for a runner to use to register with the server",
 		Action:  runGenerateActionsRunnerToken,
 		Aliases: []string{"grt"},
 		Flags: []cli.Flag{
-			cli.StringFlag{
-				Name:  "scope, s",
-				Value: "",
-				Usage: "{owner}[/{repo}] - leave empty for a global runner",
+			&cli.StringFlag{
+				Name:    "scope",
+				Aliases: []string{"s"},
+				Value:   "",
+				Usage:   "{owner}[/{repo}] - leave empty for a global runner",
 			},
 		},
 	}