refactor: cache partition_schema in `fn plan_files()`

[marvinlanhenke]

Which issue does this PR close?

Closes #361

Rationale for this change

This is a left-over part from #360 Tries to solve the unresolved issue of creating a new PartitionSchema in every iteration / or for each ManifestFile.

What changes are included in this PR?

• refactor: add creation of partition_schema to PartitionFilterCache (only if cache miss)
• refactor: clone only if cache miss
• refactor: code path in scan.rs to prepare for integration of ExpressionEvaluator and InclusiveMetricsEvaluator

Are these changes tested?

Yes. Unit tests from before.

[marvinlanhenke]

@sdd @liurenjie1024 PTAL