Refactor: based: Replace cib_operation_t booleans with enum flags

For clarity and maintainability.

The cib_op_modifies() and cib_op_can_run() functions will be removed in
an upcoming commit.

"cib_op_attr_" is a long prefix, but it clarifies that these values
represent attributes rather than operations.

Ref T658

Signed-off-by: Reid Wahl <nrwahl@protonmail.com>