[Gradle] Remove maybeRegister in favor of getOrCreate

It had a little use and even this use was causing a problem. Since
inside `maybeRegister {  }` this block Gradle forbids creation of
other entities. Because this block is part of "entity configuration".

So it is recommended to replace with either
* `getOrCreate("foo", invokeWhenCreated = {})`
* or just getOrCreate("foo").apply {}

libraries/tools/kotlin-gradle-plugin/src/common/kotlin/org/jetbrains/kotlin/gradle/plugin/sources/KotlinSourceSetFactory.kt

@@ -19,7 +19,7 @@ import org.jetbrains.kotlin.gradle.targets.js.KotlinJsCompilerAttribute
 import org.jetbrains.kotlin.gradle.targets.js.KotlinJsTarget
 import org.jetbrains.kotlin.gradle.targets.js.ir.KotlinJsIrTarget
 import org.jetbrains.kotlin.gradle.targets.metadata.isKotlinGranularMetadataEnabled
-import org.jetbrains.kotlin.gradle.utils.maybeRegister
+import org.jetbrains.kotlin.gradle.utils.getOrCreate
 import java.io.File
 
 internal abstract class KotlinSourceSetFactory<T : KotlinSourceSet> internal constructor(
@@ -94,7 +94,7 @@ internal class DefaultKotlinSourceSetFactory(
         }
 
         dependencyConfigurationWithMetadata.forEach { (configurationName, metadataName) ->
-            project.configurations.maybeRegister(metadataName) {
+            project.configurations.getOrCreate(metadataName).apply {
                 attributes.attribute(KotlinPlatformType.attribute, KotlinPlatformType.common)
                 attributes.attribute(Usage.USAGE_ATTRIBUTE, project.usageByName(KotlinUsages.KOTLIN_API))
                 attributes.attribute(Category.CATEGORY_ATTRIBUTE, project.categoryByName(Category.LIBRARY))

libraries/tools/kotlin-gradle-plugin/src/common/kotlin/org/jetbrains/kotlin/gradle/utils/ObjectCollectionExt.kt

@@ -29,18 +29,4 @@ internal fun <T> NamedDomainObjectContainer<T>.getOrCreate(
     }.get() else (if (configure != null) create(name, configure) else create(name)).also { value ->
         if (invokeWhenCreated != null) invokeWhenCreated(value)
     }
-}
-
-internal fun <T> NamedDomainObjectContainer<T>.maybeRegister(
-    name: String,
-    configure: (T.() -> Unit)? = null
-): NamedDomainObjectProvider<T> {
-    val entity = if (name in names) {
-        named(name)
-    } else {
-        register(name)
-    }
-
-    if (configure != null) entity.configure(configure)
-    return entity
 }