outputPaths not used in jib and jibDockerBuild tasks

**Environment**:

- *Jib version:* latest
- *Build tool:* gradle
- *OS:* linux

**Description of the issue**:

Settings outputPaths as follows:

outputPaths {
def baseOutputPath = project.layout.buildDirectory.dir('jib').get().file("${appName}-${version}").toString()
tar = "${baseOutputPath}.tar"
digest = "${baseOutputPath}.digest"
imageId = "${baseOutputPath}.id"
imageJson = "${baseOutputPath}.json"
}

works as expected for jibBuildTar. However, they are not generated for the jib and jibDockerBuild tasks resulting in an error there is NoSuchFile

**Expected behavior**:

jib and jibDockerBuild produce the digest, imageId, and imageJson at the locations specified (they do generate the default names if outputPaths is empty).

Also the documentation does not document the imageJson (I discovered it from the code)

**Steps to reproduce**:

1. set outputPaths with custom locations for digest, imageId, and imageJson
2. run ./gradlew jibDockerBuild
3. See it fail with NoSuchFile

**Log output**:

Execution failed for task ':jibDockerBuild'.
> java.nio.file.NoSuchFileException: /path/to/my/digest

**Additional Information**: