Extending the original TAP handler was not working as expected.
This adds a new function for displaying the log.

Ref: https://github.com/neovim/neovim/pull/10876

* tests: move "busted" dir to "test"

It is used for outputHandlers only, and clearly belongs to the tests.
Use the full module name with the `-o` option to `busted` then for
clarity.

* luacheck

* test/busted/outputHandlers/TAP.lua: use/extend upstream