pgsql: xml2: Add tests for functions xpath_nodeset() and xpath_list()

xml2: Add tests for functions xpath_nodeset() and xpath_list()

These two functions with their different argument lists have never been
tested in this module, so let's add something.

Author: Ronan Dunklau
Discussion: /messages/by-id/ZzMSJkiNZhimjXWx@paquier.xyz

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/93f9b4a93fef5dad585531692f53e42d6e9f7caf

Modified Files
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contrib/xml2/expected/xml2.out | 39 +++++++++++++++++++++++++++++++++++++++
contrib/xml2/expected/xml2_1.out | 39 +++++++++++++++++++++++++++++++++++++++
contrib/xml2/sql/xml2.sql | 16 ++++++++++++++++
3 files changed, 94 insertions(+)