Change LSP Diagnostic Symbols

[samjwill]

--local symbols = {
--    {name = "DiagnosticSignError", text = ''}, -- xf659
--    {name = "DiagnosticSignWarn", text = ''}, -- xf529
--    {name = "DiagnosticSignInfo", text = ''}, -- xf7fc
--    {name = "DiagnosticSignHint", text = ''}, -- xf835
--}