feat: add pre and post formatter autocmds (#623)

* Pre and post formatter hooks

* Ensure post hook is called

Also changes the event formatter data to only contain the name of the formatter

* Standardise autocommand names

Author: itmecho

lua/conform/runner.lua

@@ -298,6 +298,15 @@ local last_run_errored = {}
 ---@param callback fun(err?: conform.Error, output?: string[])
 ---@return integer? job_id
 local function run_formatter(bufnr, formatter, config, ctx, input_lines, opts, callback)
+  local autocmd_data = {
+    formatter = {
+      name = formatter.name,
+    },
+  }
+  vim.api.nvim_exec_autocmds("User", {
+    pattern = "ConformFormatPre",
+    data = autocmd_data,
+  })
   log.info("Run %s on %s", formatter.name, vim.api.nvim_buf_get_name(bufnr))
   log.trace("Input lines: %s", input_lines)
   callback = util.wrap_callback(callback, function(err)
@@ -309,6 +318,11 @@ local function run_formatter(bufnr, formatter, config, ctx, input_lines, opts, c
     else
       last_run_errored[formatter.name] = false
     end
+    autocmd_data["err"] = err
+    vim.api.nvim_exec_autocmds("User", {
+      pattern = "ConformFormatPost",
+      data = autocmd_data,
+    })
   end)
   if config.format then
     local err_string_cb = function(err, ...)