Use a new two-color vertex type for mapblock meshes

[Andrey2470T]

Fixes #14343 , #14091 and also it is necessary for the colored lighting support in the future.

What this does:

• Adds a new vertex type video::S3DVertex2Colors with two color attributes.
• Replaces the current vertex type of the mapblock meshes, wield and inv stacks meshes to that new type. The first color is used as the half-baked color (artificial), the second one is as the hardware one.
• Adapts all current mesh.cpp functions for working with the meshbuffers of the new type.
• Adds a direct reading the standard Irrlicht material shaders code from the substrings instead of the files in order to avoid duplicating the most part of the code.
• Forces the opengl driver to use the shader-based pipeline for the Irrlicht materials to support passing the second color as the GL_TEXTURE1 UV.

To do

This PR is a Work in Progress.

• Fix the compilation errors of the Irrlicht shaders for COpenGLDriver.
• Support the shaders-based material rendering for OGLES1/OGLES2.

How to test

Test any own nodes with the paramtype2 color, colorwallmounted, colorfacedir and color4dir with various video drivers enabled.