Add Checkbox for Marking Commit Messages as Breaking Changes

[MBeggiato]

Description:

Add a checkbox to the commit message form to let the user decide if the commit message should be marked as a breaking change. Breaking changes must be marked with an exclamation mark (!) after the commit type.

Acceptance Criteria:

Add a checkbox labeled "Breaking Change" to the form.
When the checkbox is checked, append an exclamation mark (!) after the commit type in the generated commit message.
Ensure the generated commit message follows the format: type!: message (e.g., chore!: drop support for Node 6).

Example:

If the user selects "chore" as the commit type, enters "drop support for Node 6" as the message, and checks the "Breaking Change" checkbox, the generated commit message should be: chore!: drop support for Node 6.

Additional Notes:

Ensure the checkbox is styled consistently with the rest of the form.
Update any relevant documentation to reflect this new feature.