Diagnostic reporting should use some fancy color formatting

We have this really nice diagnostic tooling in the AssertionChecker, but writing the diagnostic items should use some fancy escape characters to color code the output (but we also probably should allow that to be disabled via a flag, too).

先閱讀 AssertionChecker，並追蹤其診斷項目的寫入位置。定義預期的彩色輸出以及停用彩色輸出的 flag；完成標準是：啟用時診斷使用色彩跳脫序列，停用時保持無色彩。

由索引模型根據 Issue 內容生成。