[LL] store builtin session as cached value

to invalidate builtins on stdlib update.
It is required after making builtins use stubs of stdlib.

analysis/low-level-api-fir/src/org/jetbrains/kotlin/analysis/low/level/api/fir/project/structure/LLFirBuiltinsSessionFactory.kt

diff --git a/analysis/low-level-api-fir/src/org/jetbrains/kotlin/analysis/low/level/api/fir/project/structure/LLFirBuiltinsSessionFactory.kt b/analysis/low-level-api-fir/src/org/jetbrains/kotlin/analysis/low/level/api/fir/project/structure/LLFirBuiltinsSessionFactory.kt
index 06f8636..9add188 100644
--- a/analysis/low-level-api-fir/src/org/jetbrains/kotlin/analysis/low/level/api/fir/project/structure/LLFirBuiltinsSessionFactory.kt
+++ b/analysis/low-level-api-fir/src/org/jetbrains/kotlin/analysis/low/level/api/fir/project/structure/LLFirBuiltinsSessionFactory.kt
@@ -9,6 +9,9 @@
 import com.intellij.openapi.util.ModificationTracker
 import com.intellij.openapi.vfs.VirtualFile
 import com.intellij.psi.search.DelegatingGlobalSearchScope
+import com.intellij.psi.util.CachedValue
+import com.intellij.psi.util.CachedValueProvider
+import com.intellij.psi.util.CachedValuesManager
 import org.jetbrains.annotations.TestOnly
 import org.jetbrains.kotlin.analysis.low.level.api.fir.providers.LLFirBuiltinsAndCloneableSessionProvider
 import org.jetbrains.kotlin.analysis.low.level.api.fir.sessions.LLFirBuiltinsAndCloneableSession
@@ -53,7 +56,7 @@
 
     private val builtinsModules = ConcurrentHashMap<TargetPlatform, KtBuiltinsModule>()
 
-    private val builtinsAndCloneableSessions = ConcurrentHashMap<TargetPlatform, LLFirBuiltinsAndCloneableSession>()
+    private val builtinsAndCloneableSessions = ConcurrentHashMap<TargetPlatform, CachedValue<LLFirBuiltinsAndCloneableSession>>()
 
     /**
      * Returns the [platform]'s [KtBuiltinsModule]. [getBuiltinsModule] should be used instead of [getBuiltinsSession] when a
@@ -64,7 +67,12 @@
         builtinsModules.getOrPut(platform) { KtBuiltinsModule(platform, platform.getAnalyzerServices(), project) }
 
     fun getBuiltinsSession(platform: TargetPlatform): LLFirBuiltinsAndCloneableSession =
-        builtinsAndCloneableSessions.getOrPut(platform) { createBuiltinsAndCloneableSession(platform) }
+        builtinsAndCloneableSessions.getOrPut(platform) {
+            CachedValuesManager.getManager(project).createCachedValue {
+                val session = createBuiltinsAndCloneableSession(platform)
+                CachedValueProvider.Result(session, session.modificationTracker)
+            }
+        }.value
 
     @TestOnly
     fun clearForTheNextTest() {