Multitenancy/inbox

[NelsonVides]

This PR attempts to prepare inbox to be multitenancy ready.

NOTE, important TODOs for the near future:

• Muc, muclight, and pools, aren't multitenancy ready yet.
• Pools need to be called by their hosttype, not their lserver.

[codecov]

Codecov Report

Merging #3132 (661edf9) into master (2a0d26a) will increase coverage by 0.01%.
The diff coverage is 88.00%.

@@            Coverage Diff             @@
##           master    #3132      +/-   ##
==========================================
+ Coverage   79.45%   79.46%   +0.01%     
==========================================
  Files         395      395              
  Lines       32170    32175       +5     
==========================================
+ Hits        25560    25568       +8     
+ Misses       6610     6607       -3     

Impacted Files	Coverage Δ
src/ejabberd_sm.erl	84.51% <ø> (+0.33%)	⬆️
src/inbox/mod_inbox_entries.erl	98.33% <ø> (ø)
src/ejabberd_c2s.erl	89.00% <66.66%> (-0.28%)	⬇️
src/inbox/mod_inbox.erl	90.14% <90.00%> (-0.36%)	⬇️
src/inbox/mod_inbox_rdbms.erl	90.85% <100.00%> (ø)
src/mongoose_tcp_listener.erl	76.59% <0.00%> (-4.26%)	⬇️
src/cassandra/mongoose_cassandra_worker.erl	70.75% <0.00%> (-0.48%)	⬇️
src/mod_muc_log.erl	77.72% <0.00%> (ø)
... and 5 more

---

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[gustawlippa]

Shouldn't stop_running/2 also be changed to use HostType?

[NelsonVides]

Indeed, good one.

[chrzaszcz]

The changes looks good, my main concern is that all the execute_* functions are not converted to host types yet.

[NelsonVides]

@chrzaszcz Changes applied. When it comes to the execute queries, in reality the host passed is ignored later on, so it doesn't make any difference yet, until we can really configure more than one rdbms pool. So for now that's a big todo for the task of adapting rdbms pools.

[chrzaszcz]

We decided with @NelsonVides that adapting the backends to work with host types will be done in a follow-up PR.