The 'Install' button should offer build.gradle snippets

[mvysny]

In addition to Maven pom.xml snippets, the Install button should also offer Gradle snippets. For example, for

there should be a Gradle build.gradle snippet:

implementation("com.vaadin.componentfactory:selection-grid-flow:3.0.1")

Since Gradle defaults to Kotlin now, the snippet should be in the Kotlin syntax and should target build.gradle.kts by default. That way it's also compatible with Groovy-style build.gradle files.