feat: inform users of breaking changes on first run

[SteveLauC]

Standards checklist:

• The PR title is descriptive.
• I have read CONTRIBUTING.md
• The code compiles (cargo build)
• The code passes rustfmt (cargo fmt)
• The code passes clippy (cargo clippy)
• The code passes tests (cargo test)
• Optional: I have tested the code myself

For new steps

• Optional: Topgrade skips this step where needed
• Optional: The --dry-run option works with this step
• Optional: The --yes option works with this step if it is supported by
  the underlying command

If you developed a feature or a bug fix for someone else and you do not have the
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This PR introduces a new feature, informing our users of breaking changes if the Topgrade being executed is a major release and this execution is the first run:

$ ./target/debug/topgrade

── 09:47:31 - Topgrade 13.0.0 Breaking Changes ─────────────────────────────────
No Breaking changes

Confirmed? (y)es/(N)o

A prompt will be printed to ensure the user has confirmed these breaking changes and migrated their configuration file, if not confirmed, Topgrade won't run. This could prevent issues like #605.

[hakamadare]

@SteveLauC this is outstanding, thank you <3

[SteveLauC]

@SteveLauC this is outstanding, thank you <3

I am happy that you enjoy it:)