* Server error reply statistics.
* Error code and error strings returning from scripts.

The PR changes the error object that is raised on errors.
Instead of raising a simple Lua string, Redis will raise
a Lua table in the following format:

```
{
    err='<error message (without error code)>',
    err_code='<error code>',
    source='<User source file name>',
    line='<line where the error happned>',
    ignore_error_stats_update=true/false,
}
```

The `luaPushError` function was modified to construct
the new error table as describe above. The `luaRaiseError`
is now simply calls `lua_error` to raise the table on the
top of the Lua stack as the error object.

The `source` and `line` fields are enriched by the error
hanlder (if possible) and the `ignore_error_stats_update`
is optional and if its not present then the default value
is `false`. If `ignore_error_stats_update` is true, the
error will not be counted on the error stats.

When parsing Redis call reply, each error is translated
to a Lua table on the format describe above and the
`ignore_error_stats_update` field is set to `true` so
we will not count errors twice (we counted this error
when we invoke the command).

Example of the error stats update:

```
127.0.0.1:6379> lpush l 1
(integer) 2
127.0.0.1:6379> eval "return redis.call('get', 'l')" 0
(error) WRONGTYPE Operation against a key holding the wrong kind of value. script: e471b73f1ef44774987ab00bdf51f21fd9f7974a, on @user_script:1.
127.0.0.1:6379> info Errorstats
# Errorstats
errorstat_WRONGTYPE:count=1
127.0.0.1:6379> info commandstats
# Commandstats
cmdstat_eval:calls=1,usec=341,usec_per_call=341.00,rejected_calls=0,failed_calls=1
cmdstat_info:calls=1,usec=35,usec_per_call=35.00,rejected_calls=0,failed_calls=0
cmdstat_lpush:calls=1,usec=14,usec_per_call=14.00,rejected_calls=0,failed_calls=0
cmdstat_get:calls=1,usec=10,usec_per_call=10.00,rejected_calls=0,failed_calls=1
```

In addition we can now construct the error message (sent
as a reply to the user) from the error table, so this solves
issues where the error message was malformed and the error
code appeared in the middle of the error message:
```
127.0.0.1:6379> eval "return redis.call('set','x','y')" 0
-(error) ERR Error running script (call to 71e6319f97b0fe8bdfa1c5df3ce4489946dda479): @user_script:1: OOM command not allowed when used memory > 'maxmemory'.
+(error) OOM command not allowed when used memory > 'maxmemory'.. @user_script:1. Error running script (call to 71e6319f97b0fe8bdfa1c5df3ce4489946dda479)
```

The changes in this PR might be considered as a breaking change
for users that used Lua `pcall` function. Before the error was a
strind and now its a table. To keep backward comparability the PR
overide the `pcall` implementation and extract the error message
from the error table and return it.

Tests was added and modified to verify the changes.

* Better comments.
* Propagate flags to `afterErrorReply` and move stats update out of scripts units.
* Renamed luaRaiseError -> luaError
* Improve tests

Co-authored-by: Oran Agra <[email protected]>

1. Rename incrCommandFailedCalls -> incrCommandStatsOnError and return whether or
   not a stats value was updated
2. Revert change or `err` not including the error code.