Fix explicit api issues in kotlin-build-tools-api

Explicit api mode was not working due to the bug.

^KT-57653

compiler/build-tools/kotlin-build-tools-api/src/main/kotlin/org/jetbrains/kotlin/buildtools/api/CompilationService.kt

@@ -9,11 +9,12 @@ package org.jetbrains.kotlin.buildtools.api
  * A facade for invoking compilation in Kotlin compiler. It allows to use compiler in different modes.
  * TODO: add a mention where to see the available modes after implementing them
  */
-interface CompilationService {
+public interface CompilationService {
-    fun compile()
+    public fun compile()
 
-    companion object {
+    public companion object {
         @JvmStatic
-        fun loadImplementation(classLoader: ClassLoader) = loadImplementation(CompilationService::class, classLoader)
+        public fun loadImplementation(classLoader: ClassLoader): CompilationService =
+            loadImplementation(CompilationService::class, classLoader)
     }
 }

compiler/build-tools/kotlin-build-tools-api/src/main/kotlin/org/jetbrains/kotlin/buildtools/api/SharedApiClassesClassLoader.kt

@@ -16,7 +16,7 @@ import kotlin.reflect.KClass
  */
 @Suppress("FunctionName")
 @JvmName("newInstance")
-fun SharedApiClassesClassLoader(): ClassLoader = SharedApiClassesClassLoaderImpl(
+public fun SharedApiClassesClassLoader(): ClassLoader = SharedApiClassesClassLoaderImpl(
     SharedApiClassesClassLoaderImpl::class.java.classLoader,
     ClassLoader.getSystemClassLoader(),
     SharedApiClassesClassLoaderImpl::class.java.`package`.name,