Add `--dry-run` option to `cmd#install`

[hyuraku]

• [x] Have you followed the guidelines in our Contributing document?
• [x] Have you checked to ensure there aren't other open Pull Requests for the same change?
• [ ] Have you added an explanation of what your changes do and why you'd like us to include them?
• [ ] Have you written new tests for your changes? Here's an example.
• [x] Have you successfully run brew style with your changes locally?
• [x] Have you successfully run brew typecheck with your changes locally?
• [x] Have you successfully run brew tests with your changes locally?

---

closes https://github.com/Homebrew/brew/issues/13668

[hyuraku]

@MikeMcQuaid Would you review this PR again?

[hyuraku]

@MikeMcQuaid

Still wondering why there's no code sharing/overlap with upgrade?

I will share Upgrade#print_dry_run_dependencies in https://github.com/Homebrew/brew/blob/master/Library/Homebrew/upgrade.rb#L97. However, I wonder where we move the funcntion.

[MikeMcQuaid]

I will share Upgrade#print_dry_run_dependencies in https://github.com/Homebrew/brew/blob/master/Library/Homebrew/upgrade.rb#L97. However, I wonder where we move the funcntion.

If it's used between both upgrade and install: install.rb makes sense to me 👍🏻

[hyuraku]

@MikeMcQuaid Would you review this PR again?