v0.6.0 - API overhaul

What's Changed

• Allow strings and snowflakes for format by @jolheiser in #13
• better embed builders by @karitham in #15
• Testing/mock rw by @karitham in #14
• Change some interfaces for embed/resp helpers by @jolheiser in #16
• feat: Autocomplete by @karitham in #17
• Use InteractionRequest for incoming Interactions, attach request.Context by @jolheiser in #18

Full Changelog: v0.5.0...v0.6.0