Extract "Code Strategy Assessment Framework" into its own pattern

The Unified Source Code Inventory mentions the concept of a Source Code Strategy Assessment Framework.

I believe that such a framework could be useful even for companies that are only using a single version control system, and hence don't need to unify their source code inventory further (because they already have a single inventory).

Therefore I am proposing to pull the Source Code Strategy Assessment Framework into a pattern of its own, which can then be references from the Unified Source Code Inventory and other patterns.

從 patterns/1-initial/source-code-inventory.md 開始，檢閱 trieshard/source-strategy-assessment 中連結的 Source Code Strategy Assessment Framework。將 framework 定義為獨立的 pattern，然後更新 Unified Source Code Inventory 和其他相關 pattern，使其參照該 framework。完成的標準是：該 framework 已獨立完成文件化，且現有參照都指向它。