feature: add neotest-java to lang.java

[rcasia]

Did you check the docs?

• I have read all the LazyVim docs

Is your feature request related to a problem? Please describe.

I recently added the neotest-java adapter. Today I started using LazyVim and I wanted to try running tests in java. When I tried it I got a "No tests found" message.

Describe the solution you'd like

It would be nice to have neotest-java integrated to lang.java. (I found out LazyVim currently runs tests with mason as a workaround because there was no neotest adapter for java).

Describe alternatives you've considered

What's working for me now is to use the lang.java extra and having neotest-java as an user plugin.

-- ~/.config/nvim/lua/plugins/test.lua
return {
  { "rcasia/neotest-java" },
  {
    "nvim-neotest/neotest",
    opts = { adapters = { "neotest-java" },
    },
  },
}

Additional context

At present, neotest-java does not provide DAP support, but it will be implemented in the future.