* Change Postings back to using FOR in Lucene99PostingsFormat
We are still keeping PFOR for positions only.
This is a partial revert of https://github.com/apache/lucene/pull/69 which brings back ForDeltaUtil.
* fix merge commit
* Add forgotten forDeltaUtil calls to reader
* Addressing comments: adding Lucene90RWPostingsFormat + more
Also:
* Change to Changes.txt
* Removal of dead code which was only used in unit tests
* Removal of test code from PForUtil
* Changes.txt edit in right place now
* Apply suggestions from code review: `90 -> 99 refactoring`
Co-authored-by: gf2121 <52390227+gf2121@users.noreply.github.com>
* Remove decodeTo32 from ForUtil and regenerate
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Co-authored-by: gf2121 <52390227+gf2121@users.noreply.github.com>