chore: Updates documentation structure to have data sources and resources in subcategories by feature (#3629)

* moves docs into individual folders

* aligning file structure to hashicorp file structure

* adjust file mode

* adjusting templates

* revert unrelated change

* fixing some category headings, adjusting cluster resource to be more explicit on deprecation

* fix duplicate markdown frontmatter and align format for depreated resource/data sources

* rename Search to Atlas Search

Author: AgustinBettati