Add structured version info for tkinter

Feature or enhancement

The version of the Tcl and Tk libraries used for building _tkinter is only available as _tkinter.TCL_VERSION/TK_VERSION (strings with only major and minor, like '8.6') and tkinter.TclVersion/TkVersion (the same as floats). The full patch level is not exposed, although the module uses it (TCL_PATCH_LEVEL), and there is no structured form. The runtime version is available as Misc.info_patchlevel(), which needs a Tcl interpreter.

Add _tkinter.TCL_PATCH_LEVEL and _tkinter.TK_PATCH_LEVEL for the full build-time version strings, and tkinter.TCL_VERSION_INFO and tkinter.TK_VERSION_INFO, named tuples of the same type as returned by info_patchlevel(), with fields major, minor, micro, releaselevel and serial.

Linked PRs

• gh-157516

檢視現有的 _tkinter.TCL_VERSION/TK_VERSION 與 tkinter.TclVersion/TkVersion API，然後比較 tkinter.Misc.info_patchlevel() 的 tuple 形狀。完成的標準是公開兩個修補程式層級常數，以及兩個包含 major、minor、micro、releaselevel 和 serial 欄位的具名 tuple；gh-157516 已經連結。