X[AUTO]CLAIM should skip deleted entries (#10227)

Fix #7021 #8924 #10198

# Intro
Before this commit X[AUTO]CLAIM used to transfer deleted entries from one
PEL to another, but reply with "nil" for every such entry (instead of the entry id).
The idea (for XCLAIM) was that the caller could see this "nil", realize the entry
no longer exists, and XACK it in order to remove it from PEL.
The main problem with that approach is that it assumes there's a correlation
between the index of the "id" arguments and the array indices, which there
isn't (in case some of the input IDs to XCLAIM never existed/read):

```
127.0.0.1:6379> XADD x 1 f1 v1
"1-0"
127.0.0.1:6379> XADD x 2 f1 v1
"2-0"
127.0.0.1:6379> XADD x 3 f1 v1
"3-0"
127.0.0.1:6379> XGROUP CREATE x grp 0
OK
127.0.0.1:6379> XREADGROUP GROUP grp Alice COUNT 2 STREAMS x >
1) 1) "x"
   2) 1) 1) "1-0"
         2) 1) "f1"
            2) "v1"
      2) 1) "2-0"
         2) 1) "f1"
            2) "v1"
127.0.0.1:6379> XDEL x 1 2
(integer) 2
127.0.0.1:6379> XCLAIM x grp Bob 0 0-99 1-0 1-99 2-0
1) (nil)
2) (nil)
```

# Changes
Now,  X[AUTO]CLAIM acts in the following way:
1. If one tries to claim a deleted entry, we delete it from the PEL we found it in
  (and the group PEL too). So de facto, such entry is not claimed, just cleared
  from PEL (since anyway it doesn't exist in the stream)
2. since we never claim deleted entries, X[AUTO]CLAIM will never return "nil"
  instead of an entry.
3. add a new element to XAUTOCLAIM's response (see below)

# Knowing which entries were cleared from the PEL
The caller may want to log any entries that were found in a PEL but deleted from
the stream itself (it would suggest that there might be a bug in the application:
trimming the stream while some entries were still no processed by the consumers)

## XCLAIM
the set {XCLAIM input ids} - {XCLAIM returned ids} contains all the entry ids that were
not claimed which means they were deleted (assuming the input contains only entries
from some PEL). The user doesn't need to XACK them because XCLAIM had already
deleted them from the source PEL.

## XAUTOCLAIM
XAUTOCLAIM has a new element added to its reply: it's an array of all the deleted
stream IDs it stumbled upon.

This is somewhat of a breaking change since X[AUTO]CLAIM used to be able to reply
with "nil" and now it can't... But since it was undocumented (and generally a bad idea
to rely on it, as explained above) the breakage is not that bad.

1 files changed, 6 insertions, 0 deletions

diff --git a/src/commands/xautoclaim.json b/src/commands/xautoclaim.json
index b951eac29..726bf38fe 100644
--- a/src/commands/xautoclaim.json
+++ b/src/commands/xautoclaim.json
@@ -6,6 +6,12 @@
         "since": "6.2.0",
         "arity": -6,
         "function": "xautoclaimCommand",
+        "history": [
+            [
+                "7.0.0",
+                "Added an element to the reply array, containing deleted entries the command cleared from the PEL"
+            ]
+        ],
         "command_flags": [
             "WRITE",
             "FAST"