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"
(https://github.com/go-gitea/gitea/pull/10912#issuecomment-1137543314),
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/manager.go

@@ -9,16 +9,16 @@ import (
 
 	"code.gitea.io/gitea/modules/private"
 
-	"github.com/urfave/cli"
+	"github.com/urfave/cli/v2"
 )
 
 var (
 	// CmdManager represents the manager command
-	CmdManager = cli.Command{
+	CmdManager = &cli.Command{
 		Name:        "manager",
 		Usage:       "Manage the running gitea process",
 		Description: "This is a command for managing the running gitea process",
-		Subcommands: []cli.Command{
+		Subcommands: []*cli.Command{
 			subcmdShutdown,
 			subcmdRestart,
 			subcmdReloadTemplates,
@@ -27,80 +27,80 @@ var (
 			subCmdProcesses,
 		},
 	}
-	subcmdShutdown = cli.Command{
+	subcmdShutdown = &cli.Command{
 		Name:  "shutdown",
 		Usage: "Gracefully shutdown the running process",
 		Flags: []cli.Flag{
-			cli.BoolFlag{
+			&cli.BoolFlag{
 				Name: "debug",
 			},
 		},
 		Action: runShutdown,
 	}
-	subcmdRestart = cli.Command{
+	subcmdRestart = &cli.Command{
 		Name:  "restart",
 		Usage: "Gracefully restart the running process - (not implemented for windows servers)",
 		Flags: []cli.Flag{
-			cli.BoolFlag{
+			&cli.BoolFlag{
 				Name: "debug",
 			},
 		},
 		Action: runRestart,
 	}
-	subcmdReloadTemplates = cli.Command{
+	subcmdReloadTemplates = &cli.Command{
 		Name:  "reload-templates",
 		Usage: "Reload template files in the running process",
 		Flags: []cli.Flag{
-			cli.BoolFlag{
+			&cli.BoolFlag{
 				Name: "debug",
 			},
 		},
 		Action: runReloadTemplates,
 	}
-	subcmdFlushQueues = cli.Command{
+	subcmdFlushQueues = &cli.Command{
 		Name:   "flush-queues",
 		Usage:  "Flush queues in the running process",
 		Action: runFlushQueues,
 		Flags: []cli.Flag{
-			cli.DurationFlag{
+			&cli.DurationFlag{
 				Name:  "timeout",
 				Value: 60 * time.Second,
 				Usage: "Timeout for the flushing process",
 			},
-			cli.BoolFlag{
+			&cli.BoolFlag{
 				Name:  "non-blocking",
 				Usage: "Set to true to not wait for flush to complete before returning",
 			},
-			cli.BoolFlag{
+			&cli.BoolFlag{
 				Name: "debug",
 			},
 		},
 	}
-	subCmdProcesses = cli.Command{
+	subCmdProcesses = &cli.Command{
 		Name:   "processes",
 		Usage:  "Display running processes within the current process",
 		Action: runProcesses,
 		Flags: []cli.Flag{
-			cli.BoolFlag{
+			&cli.BoolFlag{
 				Name: "debug",
 			},
-			cli.BoolFlag{
+			&cli.BoolFlag{
 				Name:  "flat",
 				Usage: "Show processes as flat table rather than as tree",
 			},
-			cli.BoolFlag{
+			&cli.BoolFlag{
 				Name:  "no-system",
 				Usage: "Do not show system processes",
 			},
-			cli.BoolFlag{
+			&cli.BoolFlag{
 				Name:  "stacktraces",
 				Usage: "Show stacktraces",
 			},
-			cli.BoolFlag{
+			&cli.BoolFlag{
 				Name:  "json",
 				Usage: "Output as json",
 			},
-			cli.StringFlag{
+			&cli.StringFlag{
 				Name:  "cancel",
 				Usage: "Process PID to cancel. (Only available for non-system processes.)",
 			},