Create GitHub Pull Request Templates #1346

Maybe we can have some pull request templates, to help categories the type of changes, contain some checklists, explanation, and other information. Which will help contributor to have qualified pull request, and also help maintainers, reviewers, or other contributors to understand changes, join the discussion more easily!

References can be helpful here:

• https://github.com/devspace/awesome-github-templates
• https://github.com/stevemao/github-issue-templates