feat(lsp): add ability to skip lsp setup for a server

[mehalter]

Some users may want to use plugins for setting up language servers such as https://github.com/p00f/clangd_extensions.nvim or https://github.com/jose-elias-alvarez/typescript.nvim which requires you to not call the require("lspconfig")[server_name].setup call. This adds a nice user configuration for telling AstroNvim to not worry about setting up a server even if it is available.

Here is an example of setting up typescript.nvim with the new setup:

return {
  lsp = {
    skip_setup = { "tsserver" },
  },
  plugins = {
    init = {
      {
        "jose-elias-alvarez/typescript.nvim",
        after = "nvim-lsp-installer",
        config = function()
          require("typescript").setup {
            server = {
              capabilities = astronvim.lsp.capabilities,
              on_attach = astronvim.lsp.on_attach,
            },
          }
        end,
      },
    },
    ["nvim-lsp-installer"] = {
      ensure_installed = { "tsserver" },
    },
  },
}