Move class InMemoryBundleFinalizer into package org.apache.beam.runners.direct

### What happened?

Hi, @robertwb

**Issue Description**

Package **_org.apache.beam.runners.core_** is a promiscuous package, and groups together miscellaneous functionalities that might be useful to different subsystems. The package structure violates the “high cohesion and low coupling” design rules. I found that Class **_InMemoryBundleFinalizer_** is not used by classes in their package. The project has grown larger, leading to becoming increasingly hard to maintain. During the development process, one groups together classes (that often co-change) with similar responsibilities in one package to facilitate maintenance, which prevents a change that causes other packages to be modified. For example, if one modifies package **_org.apache.beam.runners.core_** (i.e., package rename), resulting in multiple classes of package **_org.apache.beam.runners.direct_** to be changed.

Location: The source file can be found at path File runners/core-java/src/main/java/org/apache/beam/runners/core

**Refactoring suggestions**

I suggest to move class **_InMemoryBundleFinalizer_** into package **_org.apache.beam.runners.direct_**.


### Issue Priority

Priority: 3

### Issue Component

Component: runner-core