[Integrated] RFR: Make it possible to only allow PRs against a select set of target branches

[Robin Westberg]

Changeset: 10552fd2
Author:    Robin Westberg <rwestberg at openjdk.org>
Date:      2020-01-24 14:08:46 +0000
URL:       https://git.openjdk.java.net/skara/commit/10552fd2

Make it possible to only allow PRs against a select set of target branches

Reviewed-by: ehelin

! bots/pr/src/main/java/org/openjdk/skara/bots/pr/CheckRun.java
! bots/pr/src/main/java/org/openjdk/skara/bots/pr/CheckWorkItem.java
! bots/pr/src/main/java/org/openjdk/skara/bots/pr/PullRequestBot.java
! bots/pr/src/main/java/org/openjdk/skara/bots/pr/PullRequestBotBuilder.java
! bots/pr/src/main/java/org/openjdk/skara/bots/pr/PullRequestBotFactory.java
! bots/pr/src/main/java/org/openjdk/skara/bots/pr/PullRequestInstance.java
! bots/pr/src/test/java/org/openjdk/skara/bots/pr/CheckTests.java