test(tests/lean/run): add some 'lost' tests

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
fix(kernel/metavar): missing justification bug

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
refactor(kernel/metavar): simplify substitution class, and remove dead code

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
refactor(kernel/metavar): simplify substitution class, and remove dead code