feat: Added routeBuilder to CustomTransition

[allanwolski]

Description

Added the routeBuilder parameter to CustomTransition to allow creating routes with CupertinoSheetRoute.
The change is simple and has no side effects.

Checklist

• The title of my PR starts with a Conventional Commit prefix (fix:, feat:, docs: etc).
• I have read the Contributor Guide and followed the process outlined for submitting PRs.
• I have updated/added tests for ALL new/updated/fixed functionality.
• I have updated/added relevant documentation in docs and added dartdoc comments with ///.
• I have updated/added relevant examples in examples.

Breaking Change

• Yes, this is a breaking change.
• No, this is not a breaking change.

Related Issues

[allanwolski]

@jacobaraujo7 consegue revisar por favor?