feat: add basic jsonnet support

ftdetect/jsonnet.lua

@@ -0,0 +1,4 @@
+vim.api.nvim_create_autocmd(
+  { "BufNewFile", "BufRead"},
+  { pattern = {"*.jsonnet", "*.libsonnet"}, command = "set ft=jsonnet" }
+)

neovim/lua/config/lsp.lua

@@ -54,6 +54,11 @@ require("lspconfig").gopls.setup{
 -- requires golangci-lint and golangci-lint-langserver
 require("lspconfig").golangci_lint_ls.setup{}
 
+-- Jsonnet
+require("lspconfig").jsonnet_ls.setup{
+  on_attach = custom_attach,
+}
+
 -- Terraform
 require("lspconfig").terraformls.setup{
   on_attach = custom_attach,