A proper boolean custom property type is commonly requested. This commit simply adds a new `IDP_BOOLEAN` type that can be used for boolean and boolean array custom properties. This can also be used for exposing boolean node sockets in the geometry nodes modifier. I've just extended the places existing IDProperty types are used, and tested with the custom property edit operator and the python console. Adding another IDProperty type is a straightforward extension of the existing design. Differential Revision: https://developer.blender.org/D12815