The solution is to also move any references to the root res directory to app/src/main/res in addition to AndroidManifest.xml.
For example, if you have a reference in your apps main config.xml file like
<resource-file src="resources/android/notification-icon.png"
target="res/drawable/notification_icon.png" />
then the target needs to be changed to look like
<resource-file src="resources/android/notification-icon.png"
target="app/src/main/res/drawable/notification_icon.png" />
in order to work on cordova-android@7.0.0 or above.
The most likely answer to this same question for most people is here:
Cordova does not create AndroidManifest.xml however, this answer is the only thing that worked on my project to solve the issue.
Credit for this discovery is due to @ryanwilliams' comment on @jcesarmobile's answer to the question linked above, highlighting that
If you have a 'res' folder in the root of your project you will still get this error even after updating the path inside plugin.xml (Due to Eclipse project detection)