FIR: disable synthetic scope, make accessor symbols synthetic

Before this commit, we had two methods to do generally the same synthetic thing.
It's an attempt to keep only one of them.
Accessor symbols are generated in Java use-site member scopes,
at this place we know better whether we are in Java class or not.
However, we have to do this at every use-site level, which is relatively slow.
Also we could encounter problems when accessor function is overridden in Kotlin,
and accessor symbol can still contain reference to Java accessor.

compiler/testData/ir/irText/expressions/jvmInstanceFieldReference.fir.txt

@@ -10,10 +10,10 @@ FILE fqName:<root> fileName:/Derived.kt
         SET_FIELD 'FIELD IR_EXTERNAL_JAVA_DECLARATION_STUB name:value type:kotlin.Int visibility:public' type=kotlin.Unit origin=null
           receiver: GET_VAR '<this>: <root>.Base declared in <root>.Base' type=<root>.Base origin=null
           value: CONST Int type=kotlin.Int value=0
-    FUN name:getValue visibility:public modality:FINAL <> ($this:<root>.Derived) returnType:IrErrorType
+    FUN name:getValue visibility:public modality:FINAL <> ($this:<root>.Derived) returnType:kotlin.Int
       $this: VALUE_PARAMETER name:<this> type:<root>.Derived
       BLOCK_BODY
-        RETURN type=kotlin.Nothing from='public final fun getValue (): IrErrorType declared in <root>.Derived'
+        RETURN type=kotlin.Nothing from='public final fun getValue (): kotlin.Int declared in <root>.Derived'
           GET_FIELD 'FIELD IR_EXTERNAL_JAVA_DECLARATION_STUB name:value type:kotlin.Int visibility:public' type=kotlin.Int origin=GET_PROPERTY
             receiver: GET_VAR '<this>: <root>.Base declared in <root>.Base' type=<root>.Base origin=null
     FUN name:setValue visibility:public modality:FINAL <> ($this:<root>.Derived, value:kotlin.Int) returnType:kotlin.Unit