FIR IDE: rewrite low level API

- Cache ModuleResolveState for module till the world changes
- Resolve every file under a lock
- All creation of raw fir files and resolve of them happens in FirFileBuilder
- Lazy resolve of fir elements happens in FirElementBuilder

Caching works like the following:
- FirModuleResolveState holds PsiToFirCache & DiagnosticsCollector & FileCacheForModuleProvider
- FileCacheForModuleProvider holds a mapping from ModuleInfo to ModuleFileCache
- ModuleFileCache caches
    - KtFile -> FirFile mapping
    - ClassId -> FirClassLikeDeclaration, CallableId -> FirCallableSymbol
        which used in corresponding FirProvider
    - mapping from declaration to it's file
        which used in corresponding FirProvider
    - locks for fir file resolving
- PsiToFirCache provides mapping from KtElement to  FirElement
- DiagnosticsCollector collects diagnostics for file and caches them

compiler/fir/tree/src/org/jetbrains/kotlin/fir/FirSession.kt

@@ -1,5 +1,5 @@
 /*
- * Copyright 2000-2018 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * Copyright 2010-2020 JetBrains s.r.o. and Kotlin Programming Language contributors.
  * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
  */
 
@@ -10,6 +10,7 @@ import org.jetbrains.kotlin.analyzer.ModuleInfo
 import org.jetbrains.kotlin.fir.types.impl.*
 import org.jetbrains.kotlin.fir.utils.ArrayMapAccessor
 import org.jetbrains.kotlin.fir.utils.ComponentArrayOwner
+import org.jetbrains.kotlin.fir.utils.NullableArrayMapAccessor
 import org.jetbrains.kotlin.fir.utils.TypeRegistry
 import org.jetbrains.kotlin.utils.Jsr305State
 import kotlin.reflect.KClass
@@ -21,6 +22,10 @@ abstract class FirSession(val sessionProvider: FirSessionProvider?) : ComponentA
         inline fun <reified T : FirSessionComponent> sessionComponentAccessor(): ArrayMapAccessor<FirSessionComponent, FirSessionComponent, T> {
             return generateAccessor(T::class)
         }
+
+        inline fun <reified T : FirSessionComponent> nullableSessionComponentAccessor(): NullableArrayMapAccessor<FirSessionComponent, FirSessionComponent, T> {
+            return generateNullableAccessor(T::class)
+        }
     }
 
     open val moduleInfo: ModuleInfo? get() = null