Fixed #171: Convert TOC block into a dynamic block and shortcode

[Nickbahson]

** Work in progress **

• Apply hierarchy for heading with their children.
• Delete un-used attributes and their definitions (ServerSideRender).
• Verify varying settings for both block attr and options settings on toc output for block and shortcode to ensure consistency.
• Apply list style to children as well
• Exclude excluded headings at $post->post_content
• Apply block deprecation
• Fix Gutenberg title attribute on the editor view.

Screenshots

TOC block editor vs save view	TOC shortcode

Includes changes from PR #165

[Closes/Fixes #171]
[Closes/Fixes #180]