User interface to info object in MAPL3

[tclune]

Because import and export fields share their ESMF info object in MAPL3, we need high level interfaces to ESMF info that component developers can use to control their attributes.

1. Some attributes are intentionally shared. An import spec can specify a list of attributes that the export spec must satisfy. Such shared specs should go into a shared part of the name space. (Provisionally this could be "MAPL/shared") The interface might be something like:

call MAPL_InfoGetShared(field, attr_name, attr_value, _RC)

(and SetShared)

2. Other attributes are intentionally private. Here the obvious namespace control is the component name as that is unique by MAPL3 requirements. "MAPL/". Of course that means the interface needs access to the component name ...

call MAPL_InfoGetPrivate(field, comp_name, attr_name, attr_value, _RC)

(and SetPrivate)

Should be a separate ticket, but we also need to figure out how to set shared attributes before components get them. Different init phases?