Windows: Declare UTF-8 through manifest

[Ghabry]

Since Windows 10 2019 update it is possible to set the app codepage to UTF-8: https://learn.microsoft.com/en-us/windows/apps/design/globalizing/use-utf8-code-page

We could add that manifest to get Unicode support in our tools on Windows for free.

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(Not worth for the Player imo as our abstraction there is already fairly good and likely not all migrated to the adware named Windows 10 xD)