Describe the pull request

This PR moves the viewport, scissor, blend factors and stencil reference states out of the render pipeline state. This allows for them to be altered without requiring a second pipeline instance. Instead, the command buffer now provides an interface to set the state accordingly.

For the Vulkan backend, this uses the VK_EXT_extended_dynamic_state extension, which has been promoted to core with Vulkan 1.3. This is a good excuse to raise the minimum required SDK version to 1.3.204.1.

Note, that it is now mandatory to set (at least) the viewport and scissor after binding a pipeline and not later than issuing a draw call, e.g.:

renderPass.begin(backBuffer);
auto& commandBuffer = renderPass.activeFrameBuffer().commandBuffer(0);
commandBuffer.use(geometryPipeline);
commandBuffer.setViewports(m_viewport.get());
commandBuffer.setScissors(m_scissor.get());

All samples and the tutorial have been updated to reflect those changes.

Known issues

Note that calling setViewports or setScissors with validation layers enabled will crash the application. This is due to a bug in the validation layer implementation, which hopefully will be resolved soon. (See #88)