Fix D3D11 renderer ignoring image flags passed to "nvgCreateImage..."

Commit 994b60b83f359232ea4a0ec4739ddf8d4d8c80d6 added/changed names of various texture flags and moved them to image creation. The D3D11 renderer simply ignores them currently and always renders textures repeated.

This adds support for the new image flags. It does so by creating additional sampler states for all possible combinations and sets the right one before each draw call (if an image is provided). I'm not entirely sure if it is the best method to accomplish this, but it works.