✨ add helper function to the command alpha generate

[Bharadwajshivam28]

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what

Introduce help to the command kubebuilder alpha generate. created a helper function named as RunGenerate which has all the logic of alpha Generate function.

when running kubebuilder alpha generate --help it gives-

It's an experimental feature that has the purpose of re-scaffolding the whole project from the scratch 
using the current version of KubeBuilder binary available.
# make sure the PROJECT file is in the 'input-dir' argument, the default is the current directory.
$ kubebuilder alpha generate --input-dir="./test" --output-dir="./my-output"
Then we will re-scaffold the project by Kubebuilder in the directory specified by 'output-dir'.

Usage:
  kubebuilder alpha generate [flags]

Flags:
  -h, --help                help for generate
      --input-dir string    path to a Kubebuilder project file if not in the current working directory
      --output-dir string   path to output the scaffolding. defaults a directory in the current working directory

Global Flags:
      --plugins strings   plugin keys to be used for this subcommand execution

Closes: #4192