Replace neotree with nvim-tree

lua/core/setup/async/project-tree.lua

@@ -0,0 +1,21 @@
+local keymaps = require('core.keymaps.async.project-tree')
+
+return function()
+  local on_attach = function(bufnr)
+    keymaps(bufnr)
+  end
+
+  -- HACK A temporary way to subscribe to the fact that
+  -- the setup is complete
+  vim.api.nvim_create_autocmd("User", {
+    pattern = "NvimTreeSetup",
+    callback = function(data)
+      on_attach(data.buf)
+    end,
+  })
+
+  require("nvim-tree").setup({
+    -- TODO uncomment this in a version that it actually works
+    -- on_attach = on_attach
+  })
+end