feat: improve use of lsp hooks in user configuration options

[ayooh]

• Improve hooks config.
  Users can simply configure the lsp hooks to be used with the Lua table. Example lazy.nvim plugin spec:

  {
    "linux-cultist/venv-selector.nvim",
    opts = {
      settings = {
        lsp_hooks = { pylsp = false },
      },
    },
  },

• Improve LspAttach event handler.
  Ruff or other lsp servers attached to the buffer will not be handled, so the value of current_pyhon_path will not be messed up. Multiple lsp notify can be prevented by the value of current_python_path and the value in venv cache file.
• Remove a duplicate unused function.
  The function merge_user_settings is also in utils.lua but is not used.

[linux-cultist]

Thank you and sorry for super late response. Will try to have a look at the code this week.