feature: move `starship/tests` to `tests` and make tests a JS package

## Overview
Converting the tests to JS will test out the starship-cli the best, since will use it to setup and run and then destroy the tests.

Inherintly there is nothing in the tests that need to be Go specific, additionally then we can also get rid of the `clients/go` since it is mostly used by the tests only.

Currently test setup is also done by the `Makefile` in tests using older versions of setup of Starship, although we should have it still just in case, but we can rid of the go part for the tests.

Start by inspecting starship/tests, the tests Makefile, clients/go, and the starship-cli entry point. Trace how the current setup, test execution, and teardown work, including the older setup retained by the Makefile. Done means tests live under tests as a JS package, use the CLI for their lifecycle, and no longer depend on the Go client where it is only used by tests.

Written by the indexing model from the issue text.