Fix leaks & performance tweaks

[Henr1k80]

• Dispose some disposables
• Avoid allocations of empty arrays
• Use ValueTuples instead of Tuples & anonymous classes
  Less allocations, performance much faster in 8+ and around the same performance in Framework
• More static
• Other minor tweaks™®©

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Rebus is MIT-licensed. The code submitted in this pull request needs to carry the MIT license too. By leaving this text in, I hereby acknowledge that the code submitted in the pull request has the MIT license and can be merged with the Rebus codebase.

[mookid8000]

Cool, thanks! 👍 Rebus 8.6.0 has the changes and is on Nuget.org now 🙂