Add platform module for publishing BOM

[nsuriadi]

#3231.

I've updated all subprojects to use the maven-publish plugin so the platform module can use the POM_ARTIFACT_ID of each subproject as opposed to project name when generating the BOM and its dependencies.

I tried to keep existing properties and functionality from the previous maven publish intact (e.g. excluding directories named internal and suppressing doclint warnings). Let me know if this isn't ideal.

[madorb]

any movement on this? would love to see a bom

[realdadfish]

Ah, found that too late. Figured out that the existing plugin can eventually be used starting with 0.17.0 and created another PR for it. But I guess going native Gradle might be the better option actually...