Validator: warn when name equals alt_name

[Famlam]

I stumbled upon ​this way (and some nearby ways with the same name). I cannot tell whether it's a common issue worldwide, or something very rare (and thus not worth adding), but perhaps the validator can catch cases where the value of name equals the value of alt_name?

Here it was introduced due to an alternative spelling (Leijenseweg rather than Leyenseweg) being used on traffic signs, which was reverted to Leyenseweg a few months later by someone in a commit called "Validatortest".

/* 19604 */
way[name][alt_name][name=*alt_name] {
  throwWarning: tr("Same value of {0} and {1}", "{0.key}", "{1.key}");
  group: tr("suspicious tag combination");
  fixRemove: "alt_name";
}

[Klumbumbus]

In 16829/josm:

• fix #19579 - Ignore generator:output:electricity and plant:output:electricity
• fix #19589 - Don't warn about duplicate housenumbers if one is tagged on a barrier=entrance or barrier=gate node
• fix #19604 - Warn if the value of alt_name is the same as of name (patch by Famlam)