basic_layout and external_sources for cmake_layout, removed meson_layout

[lasote]

Changelog: Feature: Added basic_layout, removed meson_layout and added argument src_folder to cmake_layoutas a shortcut for adjusting conanfile.folders.source.
Docs: conan-io/docs#2426

Close #10645

[memsharded]

Fantastic

[czoido]

Why cmake_layout(self, external_sources=True) and not cmake_layout(self, src_folder="whatever") ? 🤔

[lasote]

That's is a good question @czoido , cc @memsharded

[memsharded]

Why cmake_layout(self, external_sources=True) and not cmake_layout(self, src_folder="whatever")

Indeed a good question. I guess we wanted to emphasize the fact that this argument is intended to work with external sources, which was the problem being addressed. But yes, that would be more generic and flexible, lets change it.

[memsharded]

My comment can be discussed or addressed later, good for me