Add vita2d_draw_texture_resize(..., float width, float height)

[devnoname120]

The only way to stretch an image is with vita2d_draw_texture_scale().

This is not practical if I want to fit an image to a box because it takes proportions rather than resulting dimensions.

Here is a function that would solve this issue:

void vita2d_draw_texture_resize(const vita2d_texture *texture, float x, float y, float width, float height)

I might try to make a pull request if I can find some time later.

[BenMitnicK]

I must admit that I use the scale function and it is not too practical to resize an image a function like this would be no denial :)