Add GHIssueQueryBuilder to allow better filtering of issue queries

[blacelle]

Describe the feature
GitHub API enables multiple search criteria: https://docs.github.com/en/rest/reference/issues#list-repository-issues (e.g. assignee, creator, labels).

How, I can't see how one can take advantage of these parameters through the library API?

Additional context
I might have crafted manually a call similar to

    /**
     * Lists up all the issues in this repository.
     *
     * @param state
     *            the state
     * @return the paged iterable
     */
    public PagedIterable<GHIssue> listIssues(final GHIssueState state) {
        return root.createRequest()
                .with("state", state)
                .withUrlPath(getApiTailUrl("issues"))
                .toIterable(GHIssue[].class, item -> item.wrap(this));
    }

but it seems not trivial to get a reference to the root variable inside GHRepository.

Thanks

[bitwiseman]

You're right. We have a GHPullRequestQueryBuilder but not a GHIssueQueryBuilder. You could use the GHPullRequestQueryBuilder as a template or even move to having a GHIssueQueryBuilder as a base class for GHPullRequestQueryBuilder.