Switch from Apache Maven to Gradle

[oleg-nenashev]

Summary

As discussed before, we are interested in unifying the development around a single build tool, unless there is a strong need to use alternative ones. WireMock core and all the extensions use Gradle, so this repository needs an update.

References

No response

[wilsonrf]

Hi,
I would love to contribute and migrate it to Gradle, but I have some questions:

Do we want to follow what WireMock core has in its build?
For example:

1. it uses spotless, jacoco and other plugins. Do we want to adopt those plugins?
2. it has tasks to automatically bump the version (major, minor, and patch). Do we want to have the same thing?

Best regards,

Wilson

[bitxon]

I Have prepared changes that might be a good starter for migration to Gradle
#183