forge: add method diffUrl to PullRequest

[edvbld]

Hi all,

please review this small patch that adds the method PullRequest::diffUrl.
Although the implementation is the same for both GitHubPullRequest and
GitLabMergeRequest I chose to not do a default method to highlight that this
is more of a coincidence than a rule.

Thanks,
Erik

---

Progress

• Change must not contain extraneous whitespace
• Change must be properly reviewed

Reviewers

• Robin Westberg (rwestberg - Reviewer)

Download

$ git fetch https://git.openjdk.java.net/skara pull/459/head:pull/459
$ git checkout pull/459

[bridgekeeper]

👋 Welcome back ehelin! A progress list of the required criteria for merging this PR into master will be added to the body of your pull request.

[rwestberg]

Looks good!

[openjdk]

@edvbld This change now passes all automated pre-integration checks. When the change also fulfills all project specific requirements, type /integrate in a new comment to proceed. After integration, the commit message will be:

forge: add method diffUrl to PullRequest

Reviewed-by: rwestberg

• If you would like to add a summary, use the /summary command.
• To credit additional contributors, use the /contributor command.
• To add additional solved issues, use the /solves command.

Since the source branch of this PR was last updated there have been 2 commits pushed to the master branch. Since there are no conflicts, your changes will automatically be rebased on top of these commits when integrating. If you prefer to avoid automatic rebasing, please merge master into your branch, and then specify the current head hash when integrating, like this: /integrate 529eedf992434fe1af01d445a4d1f7834829a17a.

➡️ To integrate this PR with the above commit message, type /integrate in a new comment.

[edvbld]

/integrate

[openjdk]

@edvbld The following commits have been pushed to master since your change was applied:

• 529eedf: git-pr: use multi-command argument parser
• 0feb780: 283: Pull request pruner bot should look at comments and reviews only

Your commit was automatically rebased without conflicts.

Pushed as commit 513a8e3.

[mlbridge]

Webrevs

• 00: Full (89faf8e)