[kernel] add wkey 'project' for save/load warnings

src/libraries/project/project.ml

src/libraries/project/project_skeleton.ml

src/libraries/project/project_skeleton.mli

tests/misc/oracle/audit-out.json

tests/misc/oracle/my_visitor.1.res.oracle

tests/misc/oracle/orphan_emitter.res.oracle

tests/saveload/oracle/basic.0.res.oracle

tests/saveload/oracle/basic.4.res.oracle

tests/saveload/oracle/deps.1.res.oracle

tests/saveload/oracle/deps.2.res.oracle

tests/saveload/oracle/deps.4.res.oracle

tests/saveload/oracle/segfault_datatypes.res.oracle