CLI: Install @storybook/blocks package in mdx-to-csf codemod

[kasperpeulen]

Closes #21544

What I did

This installs the @storybook/blocks package in the mdx-to-csf codemod.

How to test

Migrate a storybook 6 project to storybook 7, and then run the new codemod. You should see a message that @storybook/blocks get installed, and also see that in your package.json/node_modules.

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Checklist

• Make sure your changes are tested (stories and/or unit, integration, or end-to-end tests)
• Make sure to add/update documentation regarding your changes
• If you are deprecating/removing a feature, make sure to update
  MIGRATION.MD

Maintainers

• If this PR should be tested against many or all sandboxes,
  make sure to add the ci:merged or ci:daily GH label to it.
• Make sure this PR contains one of the labels below.

["cleanup", "BREAKING CHANGE", "feature request", "bug", "documentation", "maintenance", "dependencies", "other"]