Remove unused #include's from backend .c files

as determined by include-what-you-use (IWYU)

While IWYU also suggests to *add* a bunch of #include's (which is its
main purpose), this patch does not do that.  In some cases, a more
specific #include replaces another less specific one.

Some manual adjustments of the automatic result:

- IWYU currently doesn't know about includes that provide global
  variable declarations (like -Wmissing-variable-declarations), so
  those includes are being kept manually.

- All includes for port(ability) headers are being kept for now, to
  play it safe.

- No changes of catalog/pg_foo.h to catalog/pg_foo_d.h, to keep the
  patch from exploding in size.

Note that this patch touches just *.c files, so nothing declared in
header files changes in hidden ways.

As a small example, in src/backend/access/transam/rmgr.c, some IWYU
pragma annotations are added to handle a special case there.

Discussion: https://www.postgresql.org/message-id/flat/af837490-6b2f-46df-ba05-37ea6a6653fc%40eisentraut.org

src/backend/commands/publicationcmds.c

@@ -14,7 +14,6 @@
 
 #include "postgres.h"
 
-#include "access/genam.h"
 #include "access/htup_details.h"
 #include "access/table.h"
 #include "access/xact.h"
@@ -23,7 +22,6 @@
 #include "catalog/namespace.h"
 #include "catalog/objectaccess.h"
 #include "catalog/objectaddress.h"
-#include "catalog/partition.h"
 #include "catalog/pg_database.h"
 #include "catalog/pg_inherits.h"
 #include "catalog/pg_namespace.h"
@@ -31,12 +29,10 @@
 #include "catalog/pg_publication.h"
 #include "catalog/pg_publication_namespace.h"
 #include "catalog/pg_publication_rel.h"
-#include "catalog/pg_type.h"
 #include "commands/dbcommands.h"
 #include "commands/defrem.h"
 #include "commands/event_trigger.h"
 #include "commands/publicationcmds.h"
-#include "funcapi.h"
 #include "miscadmin.h"
 #include "nodes/nodeFuncs.h"
 #include "parser/parse_clause.h"
@@ -44,10 +40,7 @@
 #include "parser/parse_relation.h"
 #include "storage/lmgr.h"
 #include "utils/acl.h"
-#include "utils/array.h"
 #include "utils/builtins.h"
-#include "utils/catcache.h"
-#include "utils/fmgroids.h"
 #include "utils/inval.h"
 #include "utils/lsyscache.h"
 #include "utils/rel.h"