Add some cases for the embed element

Signed-off-by: xiaojunwu <xiaojunx.a.wu@intel.com>
Refine tests for the embed element

- Add _manual suffix to reftest filename
- Add a reference file embed_represent_nothing_ref.html
- Remove embed_pass_parameters.html and embed_type_unmatch.html
  as not good design
Update according to the new template

1. Update the code format
2. Update the reference specification

Signed-off-by: xiaojunwu <xiaojunx.a.wu@intel.com>
Resolve issues according to review comments

1. Rename files
2. Change titles
3. Remove the tests duplicate with reflection

Signed-off-by: xiaojunwu <xiaojunx.a.wu@intel.com>
Remove trailing whitespaces
Merge pull request #454 from xiaojunwu/xiaojunwu/the-embed-element

Add tests for the embed element