Apply Artifactory Gradle plugin to build

Since gh-23282, our CI does not apply automatically the Artifactory
Gradle plugin during our build and we're now applying it "manually".
This commit backports this change since the build configuration is
shared between branches.

See gh-23282

Author: bclozel

build.gradle

@@ -14,6 +14,7 @@ plugins {
 	id "org.jetbrains.kotlin.jvm" version "1.2.71" apply false
 	id "org.jetbrains.dokka" version "0.9.18"
 	id "org.asciidoctor.convert" version "1.5.8"
+	id "com.jfrog.artifactory" version '4.9.8' apply false
 }
 
 ext {

gradle/publish-maven.gradle

@@ -1,4 +1,5 @@
 apply plugin: "propdeps-maven"
+apply plugin: 'com.jfrog.artifactory'
 
 install {
 	repositories.mavenInstaller {
@@ -58,3 +59,7 @@ def customizePom(pom, gradleProject) {
 		}
 	}
 }
+
+artifactoryPublish {
+  publishConfigs('archives')
+}