[SPARK-56690][SQL] - Expose common TaskMemoryManager API on HashedRelation to avoid code duplication

[erenavsarogullari]

What changes were proposed in this pull request?

Currently, HashedRelation creates TaskMemoryManager by duplicating same TaskMemoryManager definition on following APIs:

HashedRelation.apply()
UnsafeHashedRelation.read()
LongToUnsafeRowMap.this()

It will be useful to expose a single TaskMemoryManager creation API to avoid code duplication and this approach will be useful for the following kind of cases by managing the required logic with single definition:
https://issues.apache.org/jira/browse/SPARK-54354
#53065

Why are the changes needed?

It will be useful for long-term maintenance.

Does this PR introduce any user-facing change?

No

How was this patch tested?

Being added new UT case and existing test cases creating HashedRelation instance.

Was this patch authored or co-authored using generative AI tooling?

No