pgsql: Specify the encoding of input to fmtId()

Specify the encoding of input to fmtId()

This commit adds fmtIdEnc() and fmtQualifiedIdEnc(), which allow to specify
the encoding as an explicit argument.  Additionally setFmtEncoding() is
provided, which defines the encoding when no explicit encoding is provided, to
avoid breaking all code using fmtId().

All users of fmtId()/fmtQualifiedId() are either converted to the explicit
version or a call to setFmtEncoding() has been added.

This commit does not yet utilize the now well-defined encoding, that will
happen in a subsequent commit.

Reviewed-by: Noah Misch <noah@leadboat.com>
Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us>
Backpatch-through: 13
Security: CVE-2025-1094

Branch
------
REL_16_STABLE

Details
-------
https://git.postgresql.org/pg/commitdiff/56aa2dcddeb299f62dad98ba50ad8db47cddaf97

Modified Files
--------------
src/bin/pg_dump/pg_backup_archiver.c |  1 +
src/bin/pg_dump/pg_dump.c            |  1 +
src/bin/pg_dump/pg_dumpall.c         |  1 +
src/bin/psql/command.c               |  3 ++
src/bin/scripts/common.c             |  5 ++-
src/bin/scripts/createdb.c           |  2 +
src/bin/scripts/createuser.c         |  2 +
src/bin/scripts/dropdb.c             | 13 +++---
src/bin/scripts/dropuser.c           |  3 +-
src/bin/scripts/reindexdb.c          | 11 +++--
src/bin/scripts/vacuumdb.c           |  5 ++-
src/fe_utils/string_utils.c          | 84 +++++++++++++++++++++++++++++++++---
src/include/fe_utils/string_utils.h  |  3 ++
13 files changed, 112 insertions(+), 22 deletions(-)