Fix memory leak when decoding a property list with a virtual dataset layout

[fortnern]

The code to decode a layout encoded on a serialized DCPL has been updated to properly build the source file and dataset name hash tables, and set the "orig" fields properly so the name buffers are freed if they're not shared. This should fix the memory leaks that occurred because the orig fields were not set, as well as avoid a potential bug if a duplicate source file or dataset were added after decoding.

Addresses #5695

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Important

Fix memory leak in H5P__dcrt_layout_dec() by setting "orig" fields and building hash tables for source file and dataset names.

• Memory Management:
  • Fix memory leak in H5P__dcrt_layout_dec() by properly setting "orig" fields for source file and dataset names.
  • Ensure name buffers are freed if not shared, preventing memory leaks.
• Hash Tables:
  • Build hash tables for source file and dataset names in H5P__dcrt_layout_dec() to avoid duplicate entries.
  • Use HASH_FIND and HASH_ADD_KEYPTR to manage entries efficiently.

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[byrnHDF]

This change can be tested by executing the dailybuild on this branch in your fork (change check to ignore)