redesign of some glyphs for Shan

[YusukeShirakihara]

Hello. Thank you for providing us with great fonts.
I’d like to submit a pull request regarding Noto Sans Myanmar for Shan language support.

About a year ago, SZTSIIT made the following issue #19 and pull request #63 about some incorrect characters, sizes and positioning of numbers for Shan in Noto Sans Myanmar.
Unfortunately, however, these topics were closed by SZTSIIT himself.

I’ve been working on fonts for Shan speaking people recently, and native speakers agreed with the changes in the request above.
Since the changes are desirable, I thought I might take over and submit this PR again.
In addition to SZTSIIT’s changes, we made a few adjustments.
And this PR is only for Noto Sans Myanmar.

Sample
ႁက္ႁည္ႁႁွႁုႁူႁႂႁ်ႂႁိုႁိူ
ၾက္ၾည္ၾၾွၾုၾူၾႂၾ်ႂၾိုၾိူ
ၽက္ၽည္ၽ
ꩡꩡ︀
႐႑႒႓႔႕႖႗႘႙

Thank you for taking this request into consideration.

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