Implement InboundGroupSession::merge
Summary: This adds a merge method to InboundGroupSession.
Type: add
Test Plan: Verify unit tests pass.
We will be migrating away from GitLab to Forgejo. | 我们将从 GitLab 迁移到 Forgejo。
As GitLab is imposing a region lock for users under the rule of the Peking government, we deem this as unacceptable action, and will stop using GitLab in the near future.
鉴于 GitLab 正在对 Peking 政府治下地区人民施加锁区，我们认为这是不可接受的动作，并将在不久的将来停止使用 GitLab。
We already have Phorge at https://iron.lily-is.land , but Phorge has limited support for CI/CD, and the interaction logic is much different from GitLab. Because Forgejo has support for CI/CD, and is similar to GitLab in the interaction logic, we choose it as a drop-in replacement for GitLab.
我们已经在 https://iron.lily-is.land 上有一个 Phorge 了，但 Phorge 对 CI/CD 支持有限，而且交互逻辑跟 GitLab 很不同。因为 Forgejo 有 CI/CD 支持，跟 GitLab 在交互逻辑上差不多，我们选择它作为 GitLab 的直接替代品。
The Forgejo instance is at https://r.lily-is.land , which we expect to be usable by Jan 2025. Repositories of the Kazv Project are expected to be migrated by the end of 2025 (time edited). After that time, this GitLab instance will be archived as read-only. We will strive to keep the data for at least one year after the archiving.
Forgejo 实例在 https://r.lily-is.land ，我们预计它会在 2025年1月之前可用。the Kazv Project 的仓库预计在 2025年末（时间编辑过）之前被迁移。在那之后，这个 GitLab 实例会被只读存档。我们会尽力把数据保存到存档后至少一年的时间。
Anyone who is still using the reg.lily.kazv.moe container registry will be asked to change to use whatever is proposed by individual projects.
我们请求任何仍在使用 reg.lily.kazv.moe container registry 的人转而使用各个项目计划使用的东西。
Know more about the region lock by GitLab: | 了解更多关于 GitLab 的锁区政策： https://misskey.io/notes/a21mfq5faxaf5c0a
Summary: This adds a merge method to InboundGroupSession.
Type: add
Test Plan: Verify unit tests pass.