[Eva] floating-point widening hints

src/kernel_services/abstract_interp/fc_float.ml

src/kernel_services/abstract_interp/float_interval.ml

src/kernel_services/abstract_interp/float_interval.mli

src/kernel_services/abstract_interp/float_interval_sig.mli

src/kernel_services/abstract_interp/float_sig.mli

src/kernel_services/abstract_interp/fval.mli

src/kernel_services/abstract_interp/ival.ml

src/kernel_services/abstract_interp/ival.mli

src/kernel_services/abstract_interp/lmap.ml

src/kernel_services/abstract_interp/lmap.mli

src/kernel_services/abstract_interp/locations.ml

src/kernel_services/abstract_interp/locations.mli

src/kernel_services/abstract_interp/offsetmap.ml

src/kernel_services/abstract_interp/offsetmap.mli

...vices/abstract_interp/offsetmap_lattice_with_isotropy.mli

src/plugins/value/domains/gauges/gauges_domain.ml

src/plugins/value/domains/symbolic_locs.ml

src/plugins/value/utils/widen.ml

src/plugins/value/utils/widen.mli

src/plugins/value_types/cvalue.ml