nvim: lsp: Disable semantic token highlighting

It produces somewhat bad syntax highlighting in some cases. For example,
in typescript, the variable and it's type annotation get the same colour.

nvim/.config/nvim/lua/lsp.lua

@@ -157,6 +157,9 @@ local on_attach = function(client, bufnr)
     end
   end
 
+  -- Opt out of semantic highlighting
+  client.server_capabilities.semanticTokensProvider = nil
+
   if client.server_capabilities.codeLensProvider or client.server_capabilities.documentHighlightProvider then
     if client.server_capabilities.codeLensProvider then
       vim.api.nvim_create_autocmd({"CursorHold", "CursorHoldI", "InsertLeave"}, {