[Integrated] RFR: Add submodule and subrepo support

[Erik Helin]

Changeset: e23b2482
Author:    Erik Helin <ehelin at openjdk.org>
Date:      2019-10-22 09:21:34 +0000
URL:       https://git.openjdk.java.net/skara/commit/e23b2482

Add submodule and subrepo support

Reviewed-by: rwestberg

! jcheck/src/test/java/org/openjdk/skara/jcheck/TestRepository.java
! vcs/src/main/java/org/openjdk/skara/vcs/ReadOnlyRepository.java
! vcs/src/main/java/org/openjdk/skara/vcs/Repository.java
+ vcs/src/main/java/org/openjdk/skara/vcs/Submodule.java
! vcs/src/main/java/org/openjdk/skara/vcs/git/GitRepository.java
! vcs/src/main/java/org/openjdk/skara/vcs/hg/HgRepository.java
! vcs/src/test/java/org/openjdk/skara/vcs/RepositoryTests.java