git: openjdk/skara: 1903: Verify User's repository access when processing backport command

[Zhao Song]

Changeset: 1ac2ffa4
Author:    Zhao Song <zsong at openjdk.org>
Date:      2023-06-05 15:59:56 +0000
URL:       https://git.openjdk.org/skara/commit/1ac2ffa4e297eba8dec482bc524be87aa5becfa7

1903: Verify User's repository access when processing backport command

Reviewed-by: erikj

! bots/pr/src/main/java/org/openjdk/skara/bots/pr/BackportCommand.java
! bots/tester/src/test/java/org/openjdk/skara/bots/tester/InMemoryHostedRepository.java
! forge/src/main/java/org/openjdk/skara/forge/HostedRepository.java
! forge/src/main/java/org/openjdk/skara/forge/github/GitHubRepository.java
! forge/src/main/java/org/openjdk/skara/forge/gitlab/GitLabRepository.java
! test/src/main/java/org/openjdk/skara/test/TestHostedRepository.java