meson: Migrate imgui submodule to subproject

scripts/archive-source.sh

@@ -35,7 +35,7 @@ sub_deinit=""
 
 # xemu extras
 subprojects="$subprojects glslang SPIRV-Reflect volk VulkanMemoryAllocator
-  nv2a_vsh_cpu tomlplusplus cpp-httplib xxhash"
+  nv2a_vsh_cpu tomlplusplus cpp-httplib xxhash imgui"
 
 function cleanup() {
     local status=$?

scripts/gen-license.py

@@ -192,7 +192,7 @@ Lib('slirp', 'https://gitlab.freedesktop.org/slirp',
 Lib('imgui', 'https://github.com/ocornut/imgui',
 	mit, 'https://raw.githubusercontent.com/ocornut/imgui/master/LICENSE.txt',
 	ships_static=all_platforms,
-	submodule=Submodule('ui/thirdparty/imgui')
+	submodule=Submodule('subprojects/imgui.wrap')
 	),
 
 Lib('implot', 'https://github.com/epezent/implot',