feat: add neotest integration

[kylo252]

Neotest integrates with nvim-dap, check here. https://github.com/nvim-neotest/neotest#strategies. If no debug adapter is provided. Notify will trigger telling the user dap is not configured.

it might be better to add this to the starter.lvim. We could ask the individual language contributors add a testing section for the specific languages. I can also make a config there with the keymaps as an example of setting up testing.

Originally posted by @JBSK8NC in LunarVim/LunarVim#3227 (comment)