Split vulkan_base into smaller units

Closes #30. This is a basic refactoring of the graphics module, so
everything won't be in single file.

graphics/src/rse_graphics.cpp

@@ -0,0 +1,47 @@
+#include "rse_graphics.hpp"
+#include "window.hpp"
+#include "vulkan_base.hpp"
+
+namespace rse::graphics
+{
+
+RseGraphics::RseGraphics()
+{
+    vulkan_state = {
+        .graphicsQueue = VK_NULL_HANDLE,
+        .physicalDevice = VK_NULL_HANDLE,
+        .currentFrame = 0U,
+        .queueFamilyIndices = {0U}, /* TODO: Change when more families are needed */
+        .uniformBuffers = {},
+        .pCommandBuffers = {},
+        .descriptorSets = {},
+        .swapChainImageViews = {},
+        .swapchainExtent = {},
+        .renderPass = VK_NULL_HANDLE,
+        .descriptorSetLayout = VK_NULL_HANDLE,
+        .swapchainFramebuffers = {},
+        .graphicsPipeline = VK_NULL_HANDLE,
+        .pipelineLayout = VK_NULL_HANDLE,
+        .swapchain = VK_NULL_HANDLE,
+    };
+}
+
+uint8_t RseGraphics::graphics_run(void)
+{
+
+    window::windowInit();
+
+    if (0 != vulkanbase::initVulkan(vulkan_state))
+        return -1;
+
+    window::windowLoop(vulkan_state);
+
+    vulkanbase::deinitVulkan(vulkan_state);
+
+    window::windowTerminate();
+
+    return 0;
+}
+
+
+} // namespace rse::graphics