Restore KotlinCompilerVersion.IS_PRE_RELEASE

This commit is a slightly modified revert of 4f29c113.
IS_PRE_RELEASE allows to make LATEST_STABLE version behave as
experimental when this flag is set to true.
The general goal is to prepare fix of KT-62058; after this commit
one can do it by changing IS_PRE_RELEASE flag to true.
The fix of KT-62058 is planned to be done during bootstrapping.
This preparation and the future fix are parts of umbrella KT-61951.

compiler/util/src/org/jetbrains/kotlin/config/LanguageVersionSettings.kt

@@ -596,7 +596,7 @@ class LanguageVersionSettingsImpl @JvmOverloads constructor(
         }
     }
 
-    override fun isPreRelease(): Boolean = !languageVersion.isStable ||
+    override fun isPreRelease(): Boolean = languageVersion.isPreRelease() ||
             specificFeatures.any { (feature, state) ->
                 state == LanguageFeature.State.ENABLED && feature.forcesPreReleaseBinariesIfEnabled()
             }
@@ -607,6 +607,12 @@ class LanguageVersionSettingsImpl @JvmOverloads constructor(
     }
 }
 
+fun LanguageVersion.isPreRelease(): Boolean {
+    if (!isStable) return true
+
+    return KotlinCompilerVersion.isPreRelease() && this == LanguageVersion.LATEST_STABLE
+}
+
 fun LanguageFeature.forcesPreReleaseBinariesIfEnabled(): Boolean {
     val isFeatureNotReleasedYet = sinceVersion?.isStable != true
     return isFeatureNotReleasedYet && kind.forcesPreReleaseBinaries