gguf-split: Add option to delete split parts during merge (#26538)

gguf-split: Add option to delete split parts during merge (#26538)

* Add delete-files option to split parameters

Added a new option to delete split files during execution to free up disk space.

* Add test for delete files on merge option

* Fix tests

* Update tools/gguf-split/gguf-split.cpp

Co-authored-by: Sigbjørn Skjæret <redacted>
* Update tools/gguf-split/gguf-split.cpp

Co-authored-by: Sigbjørn Skjæret <redacted>
* Uncomment tests

* Improvements to address PR comments

* Fix formatting

* Fix formatting

* Rename --delete-files to --delete-splits

* Comment tests

* Move delete inside loop

* style cleanup

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Co-authored-by: Sigbjørn Skjæret <redacted>