* Use code snippets from managed identity credential samples in identity readme doc.
* Generate readme from snippets.
* Update snippet generation script to remove unnecessary indentation and extra new line at eof.
* Update Snippet Generation doc to show a concrete example on how to run it.
* Update other repo READMEs with the generation fixes.
* Fix KeyVault Secrets sample and use the snippets in its README
* Use the added sample snippet.
* Deprecated Azure::Core::ApplicationContext because its use is confusing and inconsistent with the original design.
---------
Co-authored-by: Rick Winter <rick.winter@microsoft.com>
Co-authored-by: Anton Kolesnyk <41349689+antkmsft@users.noreply.github.com>
Co-authored-by: Ahson Khan <ahkha@microsoft.com>
* Standardized header ordering for C++ repo
* Reordered categories to move private headers above public headers; added space between categories to enable future flexibility
