nvim: refactor luasnip as plugin

luasnip works better as a plugin and not a ftplugin

.config/nvim/plugin/luasnip.lua

@@ -0,0 +1,38 @@
+local luasnip = require("luasnip")
+local s = luasnip.snippet
+local t = luasnip.text_node
+local cr = function() return t { "", "" } end
+local i = luasnip.insert_node
+local f = luasnip.function_node
+
+local function show_date_typst_entry() return os.date('"%Y-%m-%d %H:%M:%S"') end
+luasnip.add_snippets("typst", {
+    s("entry", {
+        t("#entry("),
+        f(show_date_typst_entry),
+        t { ")[", "" },
+        t("  "),
+        i(0),
+        t { "", "]" },
+    }),
+    s("lang", {
+        t('#set text(lang: "'),
+        i(0),
+        t('")'),
+        cr(),
+    }),
+})
+
+luasnip.add_snippets("go", {
+    s("ie", {
+        t("if err != nil {"),
+        cr(),
+        t("\t"),
+        i(0),
+        cr(),
+        t("}"),
+    }),
+})
+
+local haskell_snippets = require("haskell-snippets").all
+luasnip.add_snippets("haskell", haskell_snippets, { key = "haskell" })