feat: add ability to pass args as function instead of table

[fredrikaverpil]

Fixes #186

Why?

Some users need to dynamically generate the go test command on each test run.

What?

Supply a function instead of a table as go test args:

Please give something like this a try:

return {
  {
    "nvim-neotest/neotest",
    dependencies = {
      "nvim-neotest/nvim-nio",
      "nvim-lua/plenary.nvim",
      "antoinemadec/FixCursorHold.nvim",
      "nvim-treesitter/nvim-treesitter",
      {
        "fredrikaverpil/neotest-golang", -- Installation
        branch = "args-function", -- Custom branch
      },
    },
    config = function()
      local opts = { -- Specify configuration
        go_test_args = function()
          -- Place your custom logic here for the 'go test' args
          return {
            "-v",
            "-race",
            "-count=1",
            "-coverprofile=" .. vim.fn.getcwd() .. "/coverage.out",
          }
        end,
      }
      require("neotest").setup({
        adapters = {
          require("neotest-golang")(opts), -- Apply configuration
        },
      })
    end,
  },
}