[Bug]: Misc issues with the addon

[jonniebigodes]

Describe the bug

When adding the addon to an existing Storybook via npx storybook@latest add @storybook/addon-styling-webpack there are a couple of issues that may yield some confusion and inconsistencies when running Storybook with the addon enabled.

Steps to reproduce the behavior

Running npx storybook@latest add @storybook/addon-styling-webpack prompts users with a bit of a misleading message mentioning that there are some uncommitted changes in the local repository and prompts them to continue the process or not. The only actionable item being performed is the install process, which yields a change in the repository state as the required files (i.e., package.json, yarn.lock/package-lock.json and .storybook/main.js|ts) are getting updated accordingly to account for the addon installation as shown below

We'll need to tweak the wording so that it's more clear on what's happening.

Additionally, during the installation process, users are prompted to select from a list of available options to aid in the addon's configuration. However, as displayed below, the addon adds a second addon entry to Storybook's configuration file with some configuration (that can be further optimized with some linting). I'm aware that this may be a tricky item to solve, but we should address it at some time in the near future to avoid any unwanted issues that may surface due to this misconfiguration.

Environment

Storybook Environment Info:

  System:
    OS: macOS 13.5.1
    CPU: (8) x64 Intel(R) Core(TM) i5-8257U CPU @ 1.40GHz
    Shell: 5.9 - /bin/zsh
  Binaries:
    Node: 18.16.0 - ~/.nvm/versions/node/v18.16.0/bin/node
    Yarn: 1.22.19 - /usr/local/bin/yarn <----- active
    npm: 9.5.1 - ~/.nvm/versions/node/v18.16.0/bin/npm
    pnpm: 8.1.1 - /usr/local/bin/pnpm
  Browsers:
    Chrome: 118.0.5993.117
    Edge: 116.0.1938.62
    Safari: 16.6
  npmPackages:
    @storybook/addon-essentials: ^7.5.2 => 7.5.2
    @storybook/addon-interactions: ^7.5.2 => 7.5.2
    @storybook/addon-links: ^7.5.2 => 7.5.2
    @storybook/addon-onboarding: ^1.0.8 => 1.0.8
    @storybook/addon-styling-webpack: ^0.0.5 => 0.0.5
    @storybook/blocks: ^7.5.2 => 7.5.2
    @storybook/preset-create-react-app: ^7.5.2 => 7.5.2
    @storybook/react: ^7.5.2 => 7.5.2
    @storybook/react-webpack5: ^7.5.2 => 7.5.2
    @storybook/testing-library: ^0.2.2 => 0.2.2
    storybook: ^7.5.2 => 7.5.2

Looking forward to hearing your thoughts on this @integrayshaun