Various fixes

Updates:
Replaced locally defined logical_not_t with etl::negation

Fixes:
#1228 unused parameter 'secure'
#1224 Passing a const in optional::value_or() not compiling

Pull Requests:
#1210 Fixed span reinterpret_as should return fixed span
#1211 Change generators to reflect changes in fsm.h and type_traits.h
#1217 Add const specialization for etl::get_object_at
#1218 Cleanup platform.h includes, add missing test for unaligned_type
#1221 Add test for swap
#1222 Basic string checks
#1223 Fix is_truncated in basic_string
#1225 Fix value_or not taking const in optional
#1226 Add missing include to optional
#1229 variant_legacy.h: Rename template parameters
#1231 Issue 1212 span constructor