* fixed: gradle plugin failed to be deployed

it discovered a set of issue:

Issue 1. plugin wasn't deployed in several last builds from master branch.

 Execution failed for task ':validatePlugins'.
  > Plugin validation failed with 1 problem:
      - Error: Type 'org.robovm.gradle.tasks.AbstractSimulatorTask' method 'getDeviceType()' should not be annotated with: @Internal.

fix: annotation was removed (method doesn't look as pure getter) and validatePlugins option was added to build invocation

Issue 2. its discovered that after #766 applied build failed with:

* What went wrong:
A problem occurred configuring project ':facebook-share-kit'.
> Could not create task ':facebook-share-kit:launchIPhoneSimulator'.
   > Could not create task of type 'IPhoneSimulatorTask'.
      > Could not generate a decorated class for type IPhoneSimulatorTask.
         > org/robovm/compiler/log/Logger
Caused by: java.lang.NoClassDefFoundError: org/robovm/compiler/log/Logger

root case of it: robovm-compiler dependency was excluded from shadowJar (thats a bug). But it was working as previously pom.xml contained runtime dependency to robovm-compiler (that's another bug as we produce shadowJar with merged dependencies)

Issue 3: pom.xml for gradle plugin is empty

<?xml version="1.0" encoding="UTF-8"?>
<project xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd" xmlns="http://maven.apache.org/POM/4.0.0"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
  <!-- This module was also published with a richer model, Gradle metadata,  -->
  <!-- which should be used instead. Do not delete the following line which  -->
  <!-- is to indicate to Gradle or any Gradle module metadata file consumer  -->
  <!-- that they should prefer consuming it instead. -->
  <!-- do_not_remove: published-with-gradle-metadata -->
  <modelVersion>4.0.0</modelVersion>
  <groupId>com.mobidevelop.robovm</groupId>
  <artifactId>robovm-gradle-plugin</artifactId>
  <version>2.3.22-SNAPSHOT</version>
</project>

it happens as plugin-publish uses pluginMaven publication but we set metadata for mavenJava, due another bug both pluginMaven and mavenJava are being deployed and pluginMaven overrides first (thats another issues)

Issue 4: two artifacts are being deployed under same id: `pluginMaven` and `mavenJava`

it can be observer as following warning:

Multiple publications with coordinates 'com.mobidevelop.robovm:robovm-gradle-plugin:2.3.22-SNAPSHOT' are published to repository 'mavenLocal'. The publications 'mavenJava' in root project 'robovm-gradle-plugin' and 'pluginMaven' in root project 'robovm-gradle-plugin' will overwrite each other!

Fixes:

To have single prorely configured artifact mavenJava to be removed and pluginMaven used as described in plugin-publish docs;
Caused by: java.lang.NoClassDefFoundError: org/robovm/compiler/log/Logger is fixed by removing 'exclude(dependency' -- compiler has to be packed into shadowJar

MobiVM / robovm