apply license gradle plugin

[sdelamo]

This PR applies the Gradle License Plugin. The plugin contributes a gradle task downloadLicenses which generates a license report of every dependencies.

The plugin is applied to subprojects and the root project to get an aggregated report.

./gradlew downloadLicenses
open build/reports/license/license-dependency.html

[CLAassistant]

All committers have signed the CLA.

[matrei]

To prevent bloating the root build file, could we extract this to a new file, for example: gradle/dependency-licenses.gradle?

[sdelamo]

To prevent bloating the root build file, could we extract this to a new file, for example: gradle/dependency-licenses.gradle?

@matrei I did that in 9e7b153

[matrei]

Nice, now just one more thing I saw (I'm a bit allergic to complex build files):
As we already have an allprojects block in build.gradle, we can apply the gradle/dependency-licenses.gradle file there, so we don't have to do it in multiple places:

allprojects {
    
    apply from: rootProject.layout.projectDirectory.file('gradle/dependency-licenses.gradle')

    ...
}

[matrei]

Oh, and org.grails:grails-web-fileupload is removed in 7.0.x.

If all we want is to exclude all the subprojects, could we do this instead to not have to maintain the list:

// We don't want to include any of the libraries from this repo in the license report
List<String> licenseExclusions = rootProject.subprojects.collect {
    "org.grails:${it.name}:${rootProject.projectVersion}" as String
}

and we probably want to be able to verify the list:

tasks.register('printLicenseExclusions') {
    group = 'license'
    description = 'Prints the license exclusions list'
    doLast {
        println """
            |============================================================
            |The following projects are excluded from the license report:
            |============================================================
            |${licenseExclusions.join('\n')}
        """.stripMargin()
    }
}

[matrei]

@sdelamo Sorry, for the delay in reviewing, I had not fully understood the process so my comments were left in pending state.