This was disabled explicitly in recent commit
232c948674cff1b4b72c2d6b3acfa7342d096dd1 to prevent using
the <compare> header from STL.
Now, re-enabling by implementing an ETL version of it in compare.h
* Fix compilation with -Wsign-conversion
For tests with GCC and Clang
Fixes https://github.com/ETLCPP/etl/issues/632
* Fix support of negative Id in type_lookup.h: type_from_id
* Fix element access arithmetic in atomic_gcc_sync.h fetch_add/fetch_sub
* Fix rounded_integral_division.h: divide_round_half_odd(): direction is always 1
* Fix & add more tests for year_month arithmetic
* Minor addtions to previous commit
* More missing values to be uninitialized
* Update the default constructors to = default and correct default constructor tests accordingly
* Fix & add more tests for year_month arithmetic
* Minor addtions to previous commit
* More missing values to be uninitialized
* Update the default constructors to = default and correct default constructor tests accordingly
* Restore default constructor behavior for chrono calender
