Add distinguish way English keyboard from non-English keyboard to HIToolbox.

Number:rdar://39330175 Date Originated:2018/04/11
Status:Open Resolved:
Product:macOS + SDK, Keyboards, mice and trackpads Product Version:
Classification: Reproducible:
Most input methods require keyboard layouts configuration. 
And we cloud get keyboard layouts list via `TISCreateInputSourceList`.

At most case, it need not all keyboard layouts, but English keyboard laytouts(e.g. qwerty, dvorak, colemak, and more).

But there is no way to distinguish way English keyboard from non-English keyboard.

Expected Behavior:
Get keyboard type via `TISGetInputSourceProperty`.

Actual Behavior:
 - kTISPropertyInputSourceIsASCIICapable is available, but it is not enough. It could not distinguish Qwery layout from french layout.
 - TSMInputSourcePropertyScriptCode is exists, and could distinguish English keyboard. But its behavior is not documented.

macOS High Sierra / 10.13.4 (17E199)


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