Settings loader update with basic email check, and on check abort if not valid

In the settings checker, if a regex_clean is set as None then we will abort the script with error
if the regex is not matching

Add regex check for email basic

Also add a regex_constants list with regex entries (not compiled and compiled)

src/corelibs/check_handling/regex_compiled_constants.py

@@ -0,0 +1,10 @@
+"""
+List of regex compiled strings that can be used
+"""
+
+EMAIL_REGEX_BASIC = r"""
+^[A-Za-z0-9!#$%&'*+\-\/=?^_`{|}~][A-Za-z0-9!#$%:\(\)&'*+\-\/=?^_`{|}~\.]{0,63}
+@(?!-)[A-Za-z0-9-]{1,63}(?<!-)(?:\.[A-Za-z0-9-]{1,63}(?<!-))*\.[a-zA-Z]{2,6}$
+"""
+
+# __END__