Add workflow to build and profile third-party repo (#8398)

Merge pull request 8398

.github/workflows/actions/memprof.rb

@@ -0,0 +1,14 @@
+# frozen_string_literal: true
+
+require 'jekyll'
+require 'memory_profiler'
+
+MemoryProfiler.report(allow_files: 'lib/jekyll/') do
+  Jekyll::PluginManager.require_from_bundler
+  Jekyll::Commands::Build.process({
+    "source"             => File.expand_path(ARGV[0]),
+    "destination"        => File.expand_path("#{ARGV[0]}/_site"),
+    "disable_disk_cache" => true,
+  })
+  puts ''
+end.pretty_print(scale_bytes: true, normalize_paths: true)