feat(plugins-api): Allow to manually set the plugin ID

By default, the plugin ID is derived from the class name. In some cases
this is not desired, for example, when the ID should be an abbreviation
of the class name, or when the spelling is different because the class
name follows Kotlin naming conventions. Allow manually setting the ID in
such situations.

Note that annotation parameters cannot be nullable, therefore an empty
string is set as default value for the new property.

Signed-off-by: Martin Nonnenmacher <martin.nonnenmacher@bosch.com>

plugins/api/src/main/kotlin/OrtPlugin.kt

@@ -31,6 +31,12 @@ import kotlin.reflect.KClass
  */
 @Target(AnnotationTarget.CLASS)
 annotation class OrtPlugin(
+    /**
+     * The id of the plugin. Must be unique among all plugins for the same extension point. If empty, the id is derived
+     * from the class name.
+     */
+    val id: String = "",
+
     /** The display name of the plugin. */
     val displayName: String,
 

plugins/compiler/src/main/kotlin/PluginSpecFactory.kt

@@ -61,10 +61,14 @@ class PluginSpecFactory {
 
         val pluginOptions = configClass?.getPluginOptions().orEmpty()
 
+        val pluginId = ortPlugin.id.ifEmpty {
+            pluginClass.simpleName.asString().removeSuffix(pluginParentClass.simpleName.asString())
+        }
+
         return PluginSpec(
             containingFile = pluginClass.containingFile,
             descriptor = PluginDescriptor(
-                id = pluginClass.simpleName.asString().removeSuffix(pluginParentClass.simpleName.asString()),
+                id = pluginId,
                 displayName = ortPlugin.displayName,
                 description = ortPlugin.description,
                 options = pluginOptions