extracted integration testing interface

• from: io.openapiprocessor.api.v2.OpenApiProcessorTest
• to: io.openapiprocessor.test.api.OpenApiProcessorTest with group/artifact openapi-processor:openapi-processor-test-api:<core version>

added interface to provide the target source/resource folders for integration testing:

• io.openapiprocessor.api.v2.OpenApiProcessorTest

new interface version:

• io.openapiprocessor.api.v2.OpenApiProcessor (unchanged)
• io.openapiprocessor.api.v2.OpenApiProcessorVersion new (optional) interface to provide the current version and check for a newer version.

• publish releases on maven central & snapshots on oss.sonatype.org

new interface:

• io.openapiprocessor.api.v1.Version (experimental & optional) interface to provide a version to the playground.

• another package change/improvement of the interface:
  • old package io.openapiprocessor.api.OpenApiProcessor (deprecated)
  • new package io.openapiprocessor.api.v1.OpenApiProcessor (the interface itself is the same)

• new artifact group id: io.openapiprocessor:openapi-processor:1.1.0
• added interface under new package name io.openapiprocessor.api.OpenApiProcessor. It extends from the "old" interface, i.e. using it will not break the gradle plugin (1.0.0.M7)
• marked "old" interface as deprecated

• removed (old) deprecated interface
• built cleanup

• (breaking change) renamed to openapi-processor-api

• changed version, identical to 1.0.0.B2