Add doc as 2nd parameter to validation message function

[vkarpov15]

Prerequisites

• I have written a descriptive issue title
• I have searched existing issues to ensure the feature has not already been requested

🚀 Feature Proposal

In #6523 we added the ability to set a validator's message property to a function:

    it('evaluate message function gh6523', function(done) {
      const s = mongoose.Schema({
        n: {
          type: String,
          // required: true,
          validate: {
            validator: function() {
              return false;
            },
            message: function(properties) {
              return 'fail ' + properties.value;
            }
          }
        }
      });
      const M = mongoose.model('gh6523', s);
      const m = new M({ n: 0 });

      m.validate(function(error) {
        assert.equal('fail 0', error.errors['n'].message);
        done();
      });
    });

However, there's no way to configure the return value based on the document being validated (see #12308 (reply in thread)). Would be great if you could do something like this:

            message: function(properties, doc) {
              return messages[doc.$locals.locale];
            }

Motivation

See above

Example

            message: function(properties, doc) {
              return messages[doc.$locals.locale];
            }