fix: Remove the blank line inserted between code blocks and captions

[kaushalmodi]

• [x] Remove blank lines between code blocks and their captions - https://github.com/kaushalmodi/ox-hugo/pull/646/commits/71cb5f25737c6794927273554efdac1026fd676b

  This change is part of the fix for https://github.com/kaushalmodi/ox-hugo/issues/645. The good thing is that there's no functional change in how Hugo/GoldMark (tested on Hugo v0.99.1) render these Markdown files after the change.

  So, to the user, it will be just a cosmetic change, that now there are no blank lines between code blocks and their captions.

• [x] Inside lists, remove blank line after paragraph when followed by a code block. - https://github.com/kaushalmodi/ox-hugo/pull/646/commits/9471c21fc033c8d7ab874f5f648521486c08a3f2
• [x] Inside lists, remove blank line after code block when followed by a paragraph. - https://github.com/kaushalmodi/ox-hugo/pull/646/commits/ace25a665006e23f254ecf6f4490948687916139
• [x] OK.. "remove blank line after code block when followed by a paragraph" do this only if the src or example block does not have a caption!

Fixes https://github.com/kaushalmodi/ox-hugo/issues/645.