Hello,

This PR contains various changes:

• isISO8601: added a fix for leap years checking where years divisible by 400 where not handled correctly and removed a never met condition
• isDecimal: fixed decimal point type for Egypt, Libya, Lebanon and South Africa according to the existing Wikipedia source
• rtrim and ltrim: refactored rtrim to use the same logic and added char escaping to avoid ReDOS and unwanted behavior and chars parsing by Regexp (Using \S as chars for example)
• isIdentityCard: removed the default value for locale to follow the same behavior of other validators like isPostalCode
• Added Exception testing: a new attribute error in test function add possibility to check for thrown error in validators, mainly used in working with non-existing locales.

Not very confident about adding tooling/dependencies without prior discussions but I also added istanbul/nyc , it helped me to find and fix unhandled conditions and cases and may be very useful for validator.js PRs when linked with Codecov or Coverall.

Coverage before changes:

=============================== Coverage summary ===============================
Statements   : 97.39% ( 933/958 )
Branches     : 94.5% ( 567/600 )
Functions    : 100% ( 89/89 )
Lines        : 97.53% ( 908/931 )
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Coverage after changes:

=============================== Coverage summary ===============================
Statements   : 100% ( 953/953 )
Branches     : 100% ( 586/586 )
Functions    : 100% ( 89/89 )
Lines        : 100% ( 926/926 )
================================================================================