Add the organization name and url/homepage members to PomSettings

[ShreckYe]

The PomSettings.organization member corresponds to a Maven group. The organization name and url properties are available in Maven, Gradle, and sbt. Shall we add them in PomSettings for Mill too?

I haven't added the organizationUrl/organizationHomepage member yet as I am not sure whether we stick to the former name (more similar to Maven and Gradle's) or the latter (consistent with sbt). I have added a backward-comaptible companion object apply method for the code to work with minimal modification and haven't updated the callers or the conversion buildgen code yet.

[lihaoyi]

Not sure i understand this PR; what's the difference between organization and organizationName?

[ShreckYe]

From sbt's corresponding setting keys:

  val organization = settingKey[String]("Organization/group ID.").withRank(APlusSetting)
  val organizationName = settingKey[String]("Organization full/formal name.").withRank(BMinusSetting)
  val organizationHomepage = settingKey[Option[URL]]("Organization homepage.").withRank(BMinusSetting)

From their docs:

organization := "org.example"
organizationHomepage := Some(url("http://example.org"))
homepage := Some(url("https://www.scala-sbt.org"))

[lefou]

https://maven.apache.org/pom.html#Organization