Allow to use custom mapper on Enum

[Fyro-Ing]

Allow to use custom mapper on Enum define with values parameters passed to a constructor

Fix #295

[vietj]

See also vert-x3/vertx-rx#235

[Fyro-Ing]

ok, i will check that this week-end

[vietj]

@Fyro-Ing

I think we are missing a test to ensure that the JSON generated converters will use the mapper.

Please have a look at the src/converters/resources/META-INF/vertx/json-mappers.properties file and the TestDataObject which has a methodMapped property that uses a converter for a ZonedDateTime

We need the same for this new feature.

[vietj]

@Fyro-Ing can we get the missing test soon for Vert.x 4.2 release ?

[Fyro-Ing]

I do it now

[vietj]

thanks for the contribution @Fyro-Ing @cvgaviao