feat(GlDuoChat): display attached context in chat messages

mentioned in commit 28a3b6c6

mentioned in merge request gitlab-org/editor-extensions/gitlab-jetbrains-plugin!895 (merged)

mentioned in merge request status-page!903

mentioned in merge request gitlab!164330 (merged)

mentioned in merge request gitlab-org/frontend/playground/accessibility-scanner!49 (merged)

mentioned in merge request gitlab-org/frontend/pajamas-adoption-scanner!343 (merged)

mentioned in merge request gitlab-org/gitlab-services/design.gitlab.com!4027 (merged)

mentioned in merge request gitlab!165456 (closed)