Conan 2 workspaces

[memsharded]

This ticket purpose is to gather and centralize discussion of all the other opened tickets, now that we are starting to resume work on workspaces for Conan 2.

• The idea of using CMakeDeps in [question] Can an editable package be build using only cmake commands #15880 (comment) by @mattangus needs to be explored
• Adding the capability of having local configuration (custom commands) that compose with the global cache custom commands [feature] Folder specific custom commands #16023
• Adding the capability of having local config (global.conf) in a project, and compose it with the global one: [feature] On-the-fly configuration for 2.0 #6761
• Being able to have "light" workspaces which are mostly just a list of editables: Lightweight workspaces aka Temporary editables #5566
• CMake necessary changes to make the old 1.X workspace work: [workspaces] update documentation #7206
• [question] Shared code and workspaces #5939 seems it would have been solved with new layout() definition
• The issue [workspaces] Workspaces should be Super Builds #5762 contains a large discussion, the globalness of editables need to be addressed (probably the first issue a workspace 2.X will solve)
• Issue [workspaces] Decoupled Workspaces #6844 suggests more decoupled workspaces
• Ticket [feature] Extend .conanrc for profiles information #15209 suggest to be able to have profiles locally defined by .conanrc. If considered, this would be a workspace feature.