[Milestone 4] Allow inline data to be read lazily

### Task Description

**What needs to be done:**
In the first phase of the project, the inline data is simply returned directly to the reader. We should look for ways to return a reference to this data instead so it functions similar to the out-of-line data.

**Why this task is needed:**
This will help further reduce shuffle costs for any distributed processing.

### Task Type

Code improvement/refactoring

### Related Issues

**Parent feature issue:** (if applicable )
**Related issues:**
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