Make a top-level ICE pom.xml from org.eclipse.ice.build

Created by: marshallmcdonnell

From the off-topic discussions in a closed issue, had discussions to potentially move the pom.xml file in org.eclipse.ice.build pom file to the top-level of ICE:

Key conversation links:

• Suggestion part 1: https://github.com/eclipse/ice/issues/475#issuecomment-717271343
• Suggestion part 2: https://github.com/eclipse/ice/issues/475#issuecomment-717988044
• Response: https://github.com/eclipse/ice/issues/475#issuecomment-718000006

Would like to move this to the top-level so ICE has one "main pom.xml" file. Will help using JitPack in other projects that have ICE sub-projects as dependencies (example for multi-module repo)