Improve inline src blocks

[kaushalmodi]

• Auto-escape Hugo shortcodes
• Exports HTML code elements with classes instead of plain Markdown code. This allows the user to style the inline src code differently using CSS -- Fixes Code blocks exported from src_foo blocks know their language #638.

[kaushalmodi]

Leaving this PR in draft until there's a solution to the inline src block parsing issue reported at https://lists.gnu.org/r/emacs-orgmode/2022-03/msg00008.html.

• https://lists.gnu.org/r/emacs-orgmode/2022-04/msg00088.html

---

Update (2022/05/20): Even with the above issue still in the latest Org stable as of today, there's probably no need to block this update.

[kaushalmodi]

Org example

#+begin_export html
<style>
    code.inline-src.language-nim::before {
        color: initial;
        content: "｢";
    }
    code.inline-src.language-nim::after {
        color: initial;
        content: "｣";
    }
</style>
#+end_export

In Nim, src_nim[:exports code]{echo "hello"} will print
{{{results(/hello/)}}}.

Markdown output

<style>
    code.inline-src.language-nim::before {
        color: initial;
        content: "｢";
    }
    code.inline-src.language-nim::after {
        color: initial;
        content: "｣";
    }
</style>

In Nim, <code class="inline-src language-nim" data-lang="nim">echo "hello"</code> will print
_hello_.