Require a context in assertion errors

Suggested by @andreimatei in https://github.com/cockroachdb/cockroach/pull/43032#pullrequestreview-334181315:

`AssertionFailedf` is usually called in functions with a `context.Context` available.

It would be beneficial to capture the context tags to provide more details during troubleshooting.

首先定位 AssertionFailedf 以及使用 context.Context 调用它的函数。跟踪断言错误的构造方式，以及上下文标签如何在那里可用。完成的标准是：断言错误始终需要或接收上下文，并包含其标签以便排查问题，同时为更新后的行为提供覆盖测试。

由索引模型根据 Issue 内容生成。