Add extension method to declare exchange using ExchangeDeclaration object

[hopengfoong]

Description

This should fix https://github.com/pardahlman/RawRabbit/issues/295.

Check List

• [x] All test passed.
• [x] Added documentation (if applicable).
• [x] Tests added to ensure functionality.
• [x] Pull Request to stable branch.

[pardahlman]

Thank you for this. At a first glance it all looked good - I'll try to find the time later this week to complete this PR.

[pardahlman]

Thanks!