[onert] Let's support int4 weight

[chunseoklee]

Let's prepare to support int4 weight (compiler side's issue is at #12717)

todo

• Generate model with int4 weight ( maybe single op model ) #12751
• onert loader
• onert kernel
• ...

[chunseoklee]

@seanshpark Is it possible to generate int4 weight model with circlechef(recipe?) ?

[seanshpark]

... int4 weight model with circlechef(recipe?) ?

not yet, but I hope to support within this month :)

[chunseoklee]

@seanshpark tflite2circle is able to convert tflite model(with 4bit packed weight) into circle ?

[seanshpark]

tflite2circle is able to convert tflite model(with 4bit packed weight) into circle ?

also not yet 😭
all of our tools needs update to support INT4.

[seanshpark]

please try with #12743 draft (there maybe some problems... please noti me if any)