chore(dependency): add explicit dependency of groovy-json in echo-core and echo-pipelinetriggers while upgrading groovy 3.x

[j-sandy]

While upgrading groovy 3.0.10 and spockframework 2.0-groovy-3.0, groovy-json is not part of spockframework and encounter below error during test compilation:

> Task :echo-core:compileTestGroovy
startup failed:
/echo/echo-core/src/test/groovy/com/netflix/spinnaker/echo/services/Front50ServiceSpec.groovy: 3: unable to resolve class groovy.json.JsonOutput
 @ line 3, column 1.
   import groovy.json.JsonOutput
   ^
1 error
> Task :echo-core:compileTestGroovy FAILED

> Task :echo-pipelinetriggers:compileTestGroovy
startup failed:
/echo/echo-pipelinetriggers/src/test/groovy/com/netflix/spinnaker/echo/pipelinetriggers/eventhandlers/CDEventsWebhookHandlerSpec.groovy: 28: unable to resolve class groovy.json.JsonOutput
 @ line 28, column 1.
   import groovy.json.JsonOutput
   ^
/echo/echo-pipelinetriggers/src/test/groovy/com/netflix/spinnaker/echo/pipelinetriggers/eventhandlers/PubsubEventHandlerSpec.groovy: 30: unable to resolve class groovy.json.JsonOutput
 @ line 30, column 1.
   import groovy.json.JsonOutput
   ^
2 errors
> Task :echo-pipelinetriggers:compileTestGroovy FAILED

So, adding explicit dependency of groovy-json in echo-core.gradle and echo-pipelinetriggers.gradle

With groovy 2.5.15 and spockframework 1.3-groovy-2.5, groovy-json appear as transitive dependency of spockframework as shown below:

$ ./gradlew echo-core:dI --dependency groovy-json --configuration testCompileClasspath

> Task :echo-core:dependencyInsight
org.codehaus.groovy:groovy-json:2.5.15
  Variant compile:
    | Attribute Name                 | Provided | Requested         |
    |--------------------------------|----------|-------------------|
    | org.gradle.status              | release  |                   |
    | org.gradle.category            | library  | library           |
    | org.gradle.libraryelements     | jar      | classes+resources |
    | org.gradle.usage               | java-api | java-api          |
    | org.gradle.dependency.bundling |          | external          |
    | org.gradle.jvm.environment     |          | standard-jvm      |
    | org.gradle.jvm.version         |          | 11                |
   Selection reasons:
      - By constraint
      - Forced

org.codehaus.groovy:groovy-json:2.5.15
\--- io.spinnaker.kork:kork-bom:7.190.0
     \--- testCompileClasspath

org.codehaus.groovy:groovy-json:2.5.4 -> 2.5.15
+--- org.spockframework:spock-core:1.3-groovy-2.5
|    +--- testCompileClasspath (requested org.spockframework:spock-core)
|    +--- io.spinnaker.kork:kork-bom:7.190.0
|    |    \--- testCompileClasspath
|    \--- org.spockframework:spock-spring:1.3-groovy-2.5
|         +--- testCompileClasspath (requested org.spockframework:spock-spring)
|         \--- io.spinnaker.kork:kork-bom:7.190.0 (*)
\--- org.spockframework:spock-spring:1.3-groovy-2.5 (*)

$ ./gradlew echo-pipelinetriggers:dI --dependency groovy-json --configuration testCompileClasspath

> Task :echo-pipelinetriggers:dependencyInsight
org.codehaus.groovy:groovy-json:2.5.15
  Variant compile:
    | Attribute Name                 | Provided | Requested         |
    |--------------------------------|----------|-------------------|
    | org.gradle.status              | release  |                   |
    | org.gradle.category            | library  | library           |
    | org.gradle.libraryelements     | jar      | classes+resources |
    | org.gradle.usage               | java-api | java-api          |
    | org.gradle.dependency.bundling |          | external          |
    | org.gradle.jvm.environment     |          | standard-jvm      |
    | org.gradle.jvm.version         |          | 11                |
   Selection reasons:
      - By constraint
      - Forced

org.codehaus.groovy:groovy-json:2.5.15
\--- io.spinnaker.kork:kork-bom:7.190.0
     \--- testCompileClasspath

org.codehaus.groovy:groovy-json:2.5.4 -> 2.5.15
+--- org.spockframework:spock-core:1.3-groovy-2.5
|    +--- testCompileClasspath (requested org.spockframework:spock-core)
|    +--- io.spinnaker.kork:kork-bom:7.190.0
|    |    \--- testCompileClasspath
|    \--- org.spockframework:spock-spring:1.3-groovy-2.5
|         +--- testCompileClasspath (requested org.spockframework:spock-spring)
|         \--- io.spinnaker.kork:kork-bom:7.190.0 (*)
\--- org.spockframework:spock-spring:1.3-groovy-2.5 (*)