Updated sparse packaging documentation to simplify and improve messaging (MicrosoftDocs#5275)

* Simplified instructions and updated messaging.

* Fixed broken link.

* Fixed formatting.

* Simplified manifest XML.

* Updated certificate details.

* Punctuation fix.

* Clarified absolute paths are required.

* Added space to DisplayName.

* Added keywords.

* Fixed absolute URI.

* Adjusted intro.

* Added link to "Features that require identity."

* Added note about MSIX manifest and not altering runtime behavior.

* Added note about usage of display names.

* Added using statement.

* Switched to var for consistency.

* Added await.

* Added note about excluding exe names.

* Switched to var.

* Expanded abbreviation.

* Revised intro and terminology to avoid global rename in the docs.

* Updated title to match H1.

* Specified "at runtime".

* Updated makeappx flags.

* Added clarity note about including file name.

* Added note about when the identity package is connected to the install directory.

* Changed wording about VisualElements.

* Added clarity on signing requirements.

* Updated assemblyIdentity name to match identity manifest.

* Updated version number.

* Updated application manifest naming and links.

* Renamed binaries to executables.

Author: mikebattista