cmd: migrate to urfave/cli/v2 (#24751)

This change updates our urfave/cli dependency to the v2 branch of the library.
There are some Go API changes in cli v2:

- Flag values can now be accessed using the methods ctx.Bool,
  ctx.Int, ctx.String, ... regardless of whether the flag is 'local' or
  'global'.

- v2 has built-in support for flag categories. Our home-grown category
  system is removed and the categories of flags are assigned as part of
  the flag definition.

For users, there is only one observable difference with cli v2: flags must now
strictly appear before regular arguments. For example, the following command is
now invalid:

   geth account import mykey.json --password file.txt

Instead, the command must be invoked as follows:

   geth account import --password file.txt mykey.json

cmd/evm/internal/t8ntool/utils.go

@@ -21,7 +21,7 @@ import (
 	"fmt"
 	"os"
 
-	"gopkg.in/urfave/cli.v1"
+	"github.com/urfave/cli/v2"
 )
 
 // readFile reads the json-data in the provided path and marshals into dest.