Invalid unicode characters removed from datagrid

[nicojapas]

Fixes #456

When dealing with astral symbols and ellipsing, datagrid generates invalid Unicode characters because of the use of substring().

With the regular expression /[\u{D800}-\u{DFFF}]/gu we match any character falling within the range of surrogate code points. This includes both high surrogates (0xD800 to 0xDBFF) and low surrogates (0xDC00 to 0xDFFF). So any invalid Unicode character resulting from splitting a surrogate pair is removed with replace().

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[krassowski]

Thank you for opening the PR! On conceptual level, what if someone has a table with all Unicode code points? Or if those are mapped to something else in a font. Would it be better to rewrite eliding to use Unicode-aware slice by first converting the string to an array as in https://stackoverflow.com/questions/62341685/javascript-unicode-aware-string-slice/62341816#62341816 ?

[nicojapas]

Thank you for opening the PR! On conceptual level, what if someone has a table with all Unicode code points? Or if those are mapped to something else in a font. Would it be better to rewrite eliding to use Unicode-aware slice by first converting the string to an array as in https://stackoverflow.com/questions/62341685/javascript-unicode-aware-string-slice/62341816#62341816 ?

Hi! Yes, that is a better approach I think. I just commited a new solution.

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