* remove common/constants (all in models now)
* remove common/txFlags (all in models now)
* move ecdsa from src/common to src
* move errors from src/common to src, export at top level
* sets up linting config and runs `yarn lint --fix` once, so that all changes will show up correctly in future PRs.
* Note that there are still a lot of linter errors.
* Removed deprecated functions from client.ts
* Renamed files to be camelCase
* Created top-level utils folder and tied all sub-references to it
* Grouped tests for those utils into their own section
Co-authored-by: Nathan Nichols <natenichols@cox.net>