fix: Doc comment <code> block is not rendered correctly

[filzrev]

This PR intended to fix issue #10385

What's changed on this PR

1. Modify XmlComment::ResolveCode method.
   And add empty newline before <code> tag.
2. Add unit test code to XmlCommentUnitTest.cs
3. Modify related unit test code. (Add newline to expected string )

Other Changes

• Revert some changes of fix: Broken examples problems when using inheritdoc tag #9754.
  (It seems temporary workaround is not needed on latest docfx code)
• Add snapshot test for #9736 (and #9495/#9754)
• Update snapshot test results by manually running snapshot.yml workflow.