chore: migrate to tsup

[danbillson]

An initial look into improving some of the local tooling for the node sdk

The aim of introducing bun and tsup is to speed up and simplify the process of development locally.

Bun supports ts out of the box without needing to manually transpile code before it can be executed, is fully compatible with jest but can run the test suite 10x faster.

tsup makes the build step much faster and more simple with less config and setup required.

Changes:

• replace yarn with bun for dependency management
• replace babel with tsup
• add an example which can be used to test in real time
• use bun for testing