GPUQuery: GL Backend isolation

This is part of the Vulkan task T68990.

This introduce a new GLQueryPool for managing queries in an
implementation agnostic manner.

This modify the GPU selection query to use this new object.
This also make use of blender::Vector for better code quality.

No real functionnal change.

source/blender/gpu/opengl/gl_backend.hh

@@ -32,6 +32,7 @@
 #include "gl_drawlist.hh"
 #include "gl_framebuffer.hh"
 #include "gl_index_buffer.hh"
+#include "gl_query.hh"
 #include "gl_shader.hh"
 #include "gl_texture.hh"
 #include "gl_uniform_buffer.hh"
@@ -95,6 +96,11 @@ class GLBackend : public GPUBackend {
     return new GLIndexBuf();
   };
 
+  QueryPool *querypool_alloc(void) override
+  {
+    return new GLQueryPool();
+  };
+
   Shader *shader_alloc(const char *name) override
   {
     return new GLShader(name);