HSETEX - Always issue keyspace notifications after validation

[ranshid]

In the original implementation of Hash Field Expiration (#2089), the HSETEX command was implemented to report keyspace notifications only for performed changes. This is mostly aligned with other Hash commands (for example, HDEL will also not report hdel event for items which does not exist)
The HSETEX case is somewhat different and is more like the HSET case. During HSETEX, after the command validations pass, items are ALWAYS "added" to the object, even though they might not actually be added.
This case is the same for when the hash object is empty or when all the provided fields do not exist in the object (as reported here)

This PR changes the way HSETEX will report keyspace notifications so that:

1. hset notification will ALWAYS be reported if all command validations pass.
2. hexpire will be reported in case the command include an expiration time (even past time)
3. hxpired will be reported in case the provided expiration time is in the past (or 0)
4. hdel will be reported in case the hash exists (or created as part of the command) and following the command execution it was left empty.
5. we will always return '1' as a return value of tHSETEX command which passed all validations. Before that we returned 1 only if we applied the change cross ALL the input fields, so in case some of them did not exist and a past time was set we would return 0.

[ranshid]

currently making this a draft for when #2998 is merged

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 74.86%. Comparing base (928e912) to head (33ef505).

Additional details and impacted files

@@             Coverage Diff              @@
##           unstable    #3001      +/-   ##
============================================
- Coverage     74.93%   74.86%   -0.07%     
============================================
  Files           129      129              
  Lines         71145    71147       +2     
============================================
- Hits          53310    53264      -46     
- Misses        17835    17883      +48     

Files with missing lines	Coverage Δ
src/t_hash.c	95.54% <100.00%> (+0.16%)	⬆️

... and 21 files with indirect coverage changes

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[madolson]

So, I guess we either:

1. Think this is a breaking change, and do it in 10.0
2. We think this is a bugfix, and we backport it.

Do we have a preference between those two?

[ranshid]

So, I guess we either:

1. Think this is a breaking change, and do it in 10.0
2. We think this is a bugfix, and we backport it.

Do we have a preference between those two?

TBH I am not sure how much this new feature adoption is big so I would love to make it ASAP.
Regarding the "bugfix" route - I guess this is fine by me and will save more confusion than a future "behavioural change"

[murphyjacob4]

Suggested change

[madolson]

I think this is right, and is worth backporting and calling out as a bug fix.