Update documentation, BoV chapters 1 - 5.3 (#8085)
* Update documentation chapters 1 - 5.3
Images and diagrams have not been updated,
but unnecessary images have been removed.
* Sync application declarative and architecture sections source code.
Screenshot image is updated to match the source code.
* Old datamodel image is removed.
* Ivy install image is removed.
* Remove unnecessary linking / reference
Scaled images for print edition and fixed errors up to the beginning of layouts chapter (#19835). Also major revision of Tree, CustomField, and layouts overview.