Add a copy constructor in AutomatonQuery to copy directly the compiled automaton [LUCENE-8159]

When the query is composed of multiple AutomatonQuery with the same automaton and which target different fields, it is much more efficient to reuse the already compiled automaton by copying it directly and just changing the target field.

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Migrated from [LUCENE-8159](https://issues.apache.org/jira/browse/LUCENE-8159) by Bruno Roustant (@bruno-roustant), updated Mar 05 2018
Attachments: [0001-Add-a-copy-constructor-in-AutomatonQuery-to-copy-dir.patch](https://apache.github.io/lucene-jira-archive/attachments/LUCENE-8159/0001-Add-a-copy-constructor-in-AutomatonQuery-to-copy-dir.patch), [LUCENE-8159.patch](https://apache.github.io/lucene-jira-archive/attachments/LUCENE-8159/LUCENE-8159.patch)