Update bbqueue 0.5.1

[jamesmunns]

This is a compiling set of changes that update esb to bbqueue 0.5.1. I have also updated the docs where I saw any mentions, and removed the "public EsbBuffer fields". Changelog has been updated.

Still to do:

• [ ] test on physical units (so far, just compiling and tests passing)
• [x] cargo fmt (waiting until ready to merge)
• [ ] Update version number (do in a separate PR?) + release