[Issue 19438] Add `isNormalizedPath` to std.path

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=19438

Dechcaudron <dechcaudron+issues.dlang at pm.me> changed:

           What    |Removed                     |Added
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                 CC|                            |dechcaudron+issues.dlang at pm
                   |                            |.me

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