implement Scripts, Script_Extensions, Noncharacter_Code_Point, and Default_Ignorable_Code_Point

[srghma]

related to pandaman64/lean-regex#137 (comment)

I am particularry interested in having functions like https://www.dorais.org/lean4-unicode-basic/doc/UnicodeBasic.html#Unicode.isAlphabetic but

def Unicode.isKhmer (char : Char): Bool := -- same as \p{Script=Khmer}
def Unicode.isCyrillic (char : Char): Bool := -- same as \p{Script=Cyrillic}

etc (if it makes sense). Tnx

[fgdorais]

Looks reasonably easy to implement. Thanks!

[fgdorais]

Default_Ignorable_Code_Point was added in #113

[fgdorais]

Noncharacter_Code_Point was added in #114

[fgdorais]

Script support was added in #126

[fgdorais]

I was planning on asking for additional input regarding Script_Extensions before this issue reaches its half year anniversary. However, I just noticed that @srghma has been doing a lot of work on their own. Please contact me so we can chat about your excellent work and plan for integration into UnicodeBasic.