fix(snippet): Double $ in snippet template

Closes #207

Due to $ being automatically interpreted as snippet variables, we need
to double the $ in the template to let it pass when generating the
snippet. Solves issues with php parameters that have their $ deleted
when using snippets.

lua/neogen/snippet.lua

@@ -48,6 +48,13 @@ snippet.engines = {}
 ---@private
 snippet.to_snippet = function(template, marks, pos)
     local offset, ph = {}, {}
+
+    -- Add double $ for template before creating the snippet so that text with $ (such as parameters in php)
+    -- are not interpreted as snippet
+    for i, str in ipairs(template) do
+        template[i] = str:gsub("%$", "$$") -- Escape $
+    end
+
     for i, m in ipairs(marks) do
         local r, col = m.row - pos[1] + 1, m.col
         ph[i] = (m.text and conf.enable_placeholders) and string.format("${%d:%s}", i, m.text) or "$" .. i
@@ -81,6 +88,8 @@ snippet.engines.luasnip = function(snip, pos)
     -- Convert the snippet to string
     local _snip = table.concat(snip, "\n")
 
+    vim.print(snip)
+
     ls.snip_expand(
 
         ls.s("", ls.parser.parse_snippet(nil, _snip, { trim_empty = false, dedent = false }), {