Support for gradle configuration cache

[JohannesRudolph]

The plugin currently does not support the gradle configuration cache because the Tasks declared by the plugin do not meet Gradle's requirements for serializing their state into the configuration cache.

I'd really like to use the configuration cache to speed up builds.

For example, these are errors raised by gradle when enabling the configuration cache (e.g. via gradle --configuration-cache build)

Configuration cache state could not be cached: field `_dateFormat` of `com.fasterxml.jackson.databind.cfg.BaseSettings` bean found in field `_base` of `com.fasterxml.jackson.databind.DeserializationConfig` bean found in field `_deserializationConfig` of `com.fasterxml.jackson.databind.json.JsonMapper` bean found in field `objectMapper` of task `:meshfed:simple:openapi` of type `com.epages.restdocs.apispec.gradle.OpenApiTask`: error writing value of type 'com.fasterxml.jackson.databind.util.StdDateFormat

Unable to make field protected java.util.Calendar java.text.DateFormat.calendar accessible: module java.base does not "opens java.text" to unnamed module @668a9772