[C++][Docs] Re-Organize the Existing Acero Streaming Engine Documentation

[asfimport]

The current document is too-length. By creating sub-pages for each example and explain the code and provide a better description, that would be much better in terms of readability and browsing the content. The idea is to create a sub-folder in the examples called 'aceroand include each example in a separate.cc` file. This is the code change. Following this, the documentation page on the website can be splitted into sub-pages. This is the only change suggested for this sub-task. 

There is already a JIRA: https://github.com/apache/arrow/issues/20284 to improve the internal content. So it would be used for re-writing the contnet. 

Reporter: Vibhatha Lakmal Abeykoon / @vibhatha
Assignee: Vibhatha Lakmal Abeykoon / @vibhatha

Related issues:

• [C++][Documentation] Update overview of Arrow components/layers (relates to)
• [Docs] Improve Acero Documentation (relates to)

PRs and other links:

• GitHub Pull Request #13713
• GitHub Pull Request #14185

_{Note: This issue was originally created as ARROW-17177. Please see the migration documentation for further details.}

[asfimport]

Aldrin Montana / @drin:
Linking related JIRAs for improving Acero documentation and updating the overview of components and layers

[asfimport]

Vibhatha Lakmal Abeykoon / @vibhatha:
Decided to keep the original example in a single .cc file rather than splitting it. But documentation is formatted and organized better. There is a separate effort to improve the content for each example.