pgsql: Add PQencryptPasswordConn function to libpq, use it in psql and

Add PQencryptPasswordConn function to libpq, use it in psql and createuser.

The new function supports creating SCRAM verifiers, in addition to md5
hashes. The algorithm is chosen based on password_encryption, by default.

This fixes the issue reported by Jeff Janes, that there was previously
no way to create a SCRAM verifier with "\password".

Michael Paquier and me

Discussion: https://www.postgresql.org/message-id/CAMkU%3D1wfBgFPbfAMYZQE78p%3DVhZX7nN86aWkp0QcCp%3D%2BKxZ%3Dbg%40mail.gmail.com

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/8f8b9be51fd788bb11276df89606bc653163524e

Modified Files
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doc/src/sgml/libpq.sgml | 67 ++++++++++++++++---
src/backend/libpq/auth-scram.c | 51 ++------------
src/backend/libpq/crypt.c | 2 +-
src/bin/psql/command.c | 4 +-
src/bin/scripts/createuser.c | 9 ++-
src/common/scram-common.c | 64 ++++++++++++++++++
src/include/common/scram-common.h | 3 +
src/include/libpq/scram.h | 4 +-
src/interfaces/libpq/exports.txt | 1 +
src/interfaces/libpq/fe-auth-scram.c | 35 ++++++++++
src/interfaces/libpq/fe-auth.c | 125 +++++++++++++++++++++++++++++++----
src/interfaces/libpq/fe-auth.h | 1 +
src/interfaces/libpq/libpq-fe.h | 1 +
13 files changed, 291 insertions(+), 76 deletions(-)