Add advanced_html_css folder

[01zulfi]

Complete the following REQUIRED checkboxes:

• I have thoroughly read and understand The Odin Project Contributing Guide
• The title of this PR follows the location of change: brief description of change format, e.g. Intro to HTML and CSS lesson: Fix link text

Complete the following checkboxes ONLY IF they are applicable to your PR. You can complete them later if they are not currently applicable:

• I have previewed all lesson files included in this PR with the Markdown preview tool to ensure the Markdown content is formatted correctly
• I have ensured all lesson files included in this PR follow the Layout Style Guide

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1. Because:

• Related to Cleaning up folder/file structure in the curriculum repository top-meta#109

2. This PR:

1. Moves all Advanced HTML/CSS lessons from html_css folder to the new advanced_html_css folder.
2. Renames files to snake_case where applicable.
3. Adds img subfolder where applicable.

3. Additional Information:

html_css folder will be renamed to intermediate_html_css in a future pull request.

[KevinMulhern]

Merging so we can test the changes on the review app