[FIR] Move ReturnTypeCalculator to :fir:providers module

Also make it an abstract class and turn ReturnTypeCalculatorForFullBodyResolve
  into object (because it has no state and there is no need to create
  different instances of it)

compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/transformers/body/resolve/FirBodyResolveTransformer.kt

@@ -20,7 +20,6 @@ import org.jetbrains.kotlin.fir.resolve.transformers.FirProviderInterceptor
 import org.jetbrains.kotlin.fir.resolve.transformers.ReturnTypeCalculator
 import org.jetbrains.kotlin.fir.resolve.transformers.ReturnTypeCalculatorForFullBodyResolve
 import org.jetbrains.kotlin.fir.resolve.transformers.ScopeClassDeclaration
-import org.jetbrains.kotlin.fir.scopes.FirCompositeScope
 import org.jetbrains.kotlin.fir.types.*
 import org.jetbrains.kotlin.fir.visitors.FirTransformer
 
@@ -29,7 +28,7 @@ open class FirBodyResolveTransformer(
     phase: FirResolvePhase,
     override var implicitTypeOnly: Boolean,
     scopeSession: ScopeSession,
-    val returnTypeCalculator: ReturnTypeCalculator = ReturnTypeCalculatorForFullBodyResolve(),
+    val returnTypeCalculator: ReturnTypeCalculator = ReturnTypeCalculatorForFullBodyResolve,
     outerBodyResolveContext: BodyResolveContext? = null,
     val firTowerDataContextCollector: FirTowerDataContextCollector? = null,
     val firProviderInterceptor: FirProviderInterceptor? = null,

compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/transformers/body/resolve/FirImplicitBodyResolve.kt

@@ -204,7 +204,7 @@ private class ReturnTypeCalculatorWithJump(
         returnTypeCalculator: ReturnTypeCalculator,
         outerBodyResolveContext: BodyResolveContext?
     ) -> FirDesignatedBodyResolveTransformerForReturnTypeCalculator = ::FirDesignatedBodyResolveTransformerForReturnTypeCalculator,
-) : ReturnTypeCalculator {
+) : ReturnTypeCalculator() {
 
     @OptIn(PrivateForInline::class)
     var outerBodyResolveContext: BodyResolveContext? = null

compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/transformers/contracts/FirContractResolveTransformerAdapter.kt

@@ -42,7 +42,7 @@ fun <F : FirClassLikeDeclaration> F.runContractResolveForLocalClass(
     targetedClasses: Set<FirClassLikeDeclaration>
 ): F {
     val newContext = outerBodyResolveContext.createSnapshotForLocalClasses(
-        ReturnTypeCalculatorForFullBodyResolve(),
+        ReturnTypeCalculatorForFullBodyResolve,
         targetedClasses
     )
     val transformer = FirContractResolveTransformer(session, scopeSession, newContext)