By default prevent cross slot operations in functions and scripts with # (#10615)

Adds the `allow-cross-slot-keys` flag to Eval scripts and Functions to allow
scripts to access keys from multiple slots.
The default behavior is now that they are not allowed to do that (unlike before).
This is a breaking change for 7.0 release candidates (to be part of 7.0.0), but
not for previous redis releases since EVAL without shebang isn't doing this check.

Note that the check is done on both the keys declared by the EVAL / FCALL command
arguments, and also the ones used by the script when making a `redis.call`.

A note about the implementation, there seems to have been some confusion
about allowing access to non local keys. I thought I missed something in our
wider conversation, but Redis scripts do block access to non-local keys.
So the issue was just about cross slots being accessed.

tests/unit/moduleapi/cluster.tcl

@@ -2,22 +2,6 @@
 
 source tests/support/cli.tcl
 
-proc cluster_info {r field} {
-    if {[regexp "^$field:(.*?)\r\n" [$r cluster info] _ value]} {
-        set _ $value
-    }
-}
-
-# Provide easy access to CLUSTER INFO properties. Same semantic as "proc s".
-proc csi {args} {
-    set level 0
-    if {[string is integer [lindex $args 0]]} {
-        set level [lindex $args 0]
-        set args [lrange $args 1 end]
-    }
-    cluster_info [srv $level "client"] [lindex $args 0]
-}
-
 set testmodule [file normalize tests/modules/blockonkeys.so]
 set testmodule_nokey [file normalize tests/modules/blockonbackground.so]
 set testmodule_blockedclient [file normalize tests/modules/blockedclient.so]