Add table of differences to Migrate from Newtonsoft.Json doc (#16704)

* add table of differences

* address feedback

* fix copy-paste error

* icons

* fix icon

* fix find-replace error

* use emojis instead

* move jsondocument etc out of table

* remove image files

* feedback

* address feedback

* Update docs/standard/serialization/system-text-json-migrate-from-newtonsoft-how-to.md

Co-Authored-By: Ahson Khan <[email protected]>

* remove extraneous newline

Co-authored-by: Ahson Khan <[email protected]>

Author: tdykstra