[C++][Documentation] Update overview of Arrow components/layers

[asfimport]

New components have been added/modified in Arrow (e.g., query engine), so we should update documentation that describes these. Overview of Arrow layers are described in overview.rst.

Reporter: Eduardo Ponce / @edponce

Related issues:

• [C++][Docs] Re-Organize the Existing Acero Streaming Engine Documentation (is related to)

_{Note: This issue was originally created as ARROW-14729. Please see the migration documentation for further details.}

[asfimport]

David Li / @lidavidm:
@9prady9 are you still working on this? I'm looking at the docs overall and might want to just fold this into that

[asfimport]

Pradeep Garigipati / @9prady9:
@lidavidm Sure, please take it over, I haven't started on this yet even though I have it assigned.