Add Unicode version for CMP_LoadTexture/CMP_SaveTexture

[vergol]

Add Unicode version for CMP_LoadTexture/CMP_SaveTexture

CMP_LoadTexture(const wchar_t *sourceFile, CMP_MipSet *pMipSet);
CMP_SaveTexture(const wchar_t *destFile, CMP_MipSet *pMipSet);

[Denis Levesque]

@vergol Thanks for the issue report.

For our future reference, this is one of a few unicode-related issues that have been opened (others are: #232 and #220).

[seragh]

In case this is just force of habit: https://learn.microsoft.com/en-us/windows/apps/design/globalizing/use-utf8-code-page