pgsql: SQL/JSON: Improve error-handling of JsonBehavior expressions

SQL/JSON: Improve error-handling of JsonBehavior expressions

Instead of returning a NULL when the JsonBehavior expression value
could not be coerced to the RETURNING type, throw the error message
informing the user that it is the JsonBehavior expression that caused
the error with the actual coercion error message shown in its DETAIL
line.

Discussion: https://postgr.es/m/CACJufxEo4sUjKCYtda0_qt9tazqqKPmF1cqhW9KBOUeJFqQd2g@mail.gmail.com
Backpatch-through: 17

Branch
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REL_17_STABLE

Details
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https://git.postgresql.org/pg/commitdiff/d1dc4ae5608d9c0e83d5b5d32de238a7ac3d9a1a

Modified Files
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src/backend/executor/execExprInterp.c            | 78 +++++++++++++++++++++---
src/test/regress/expected/sqljson_jsontable.out  |  7 +--
src/test/regress/expected/sqljson_queryfuncs.out | 21 ++-----
3 files changed, 78 insertions(+), 28 deletions(-)