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/generate.go

@@ -11,43 +11,43 @@ import (
 	"code.gitea.io/gitea/modules/generate"
 
 	"github.com/mattn/go-isatty"
-	"github.com/urfave/cli"
+	"github.com/urfave/cli/v2"
 )
 
 var (
 	// CmdGenerate represents the available generate sub-command.
-	CmdGenerate = cli.Command{
+	CmdGenerate = &cli.Command{
 		Name:  "generate",
 		Usage: "Command line interface for running generators",
-		Subcommands: []cli.Command{
+		Subcommands: []*cli.Command{
 			subcmdSecret,
 		},
 	}
 
-	subcmdSecret = cli.Command{
+	subcmdSecret = &cli.Command{
 		Name:  "secret",
 		Usage: "Generate a secret token",
-		Subcommands: []cli.Command{
+		Subcommands: []*cli.Command{
 			microcmdGenerateInternalToken,
 			microcmdGenerateLfsJwtSecret,
 			microcmdGenerateSecretKey,
 		},
 	}
 
-	microcmdGenerateInternalToken = cli.Command{
+	microcmdGenerateInternalToken = &cli.Command{
 		Name:   "INTERNAL_TOKEN",
 		Usage:  "Generate a new INTERNAL_TOKEN",
 		Action: runGenerateInternalToken,
 	}
 
-	microcmdGenerateLfsJwtSecret = cli.Command{
+	microcmdGenerateLfsJwtSecret = &cli.Command{
 		Name:    "JWT_SECRET",
 		Aliases: []string{"LFS_JWT_SECRET"},
 		Usage:   "Generate a new JWT_SECRET",
 		Action:  runGenerateLfsJwtSecret,
 	}
 
-	microcmdGenerateSecretKey = cli.Command{
+	microcmdGenerateSecretKey = &cli.Command{
 		Name:   "SECRET_KEY",
 		Usage:  "Generate a new SECRET_KEY",
 		Action: runGenerateSecretKey,