Multi tenancy config

[DenysGonchar]

This PR addresses #

• parsing of the host_type configuration
• init modules per host type
• Extension of gen_mod behaviour with extra callback to define modules capabilities.
• crashing if configured modules don’t support multi-tenancy.

see test/config_parser_SUITE_data/host_types.toml file for example of the new config format.

[codecov]

Codecov Report

Merging #3053 (2fee51f) into multi-tenancy-phase-1 (e5ec74a) will increase coverage by 0.06%.
The diff coverage is 96.36%.

@@                    Coverage Diff                    @@
##           multi-tenancy-phase-1    #3053      +/-   ##
=========================================================
+ Coverage                  78.05%   78.11%   +0.06%     
=========================================================
  Files                        374      374              
  Lines                      31200    31245      +45     
=========================================================
+ Hits                       24352    24406      +54     
+ Misses                      6848     6839       -9     

Impacted Files	Coverage Δ
src/config/mongoose_config_parser.erl	88.88% <93.33%> (+8.88%)	⬆️
src/config/mongoose_config_parser_toml.erl	98.59% <100.00%> (+2.24%)	⬆️
src/config/mongoose_config_spec.erl	98.84% <100.00%> (+0.04%)	⬆️
src/gen_mod.erl	75.00% <100.00%> (+0.67%)	⬆️
...bal_distrib/mod_global_distrib_hosts_refresher.erl	73.58% <0.00%> (-3.78%)	⬇️
src/wpool/mongoose_wpool.erl	81.00% <0.00%> (-1.00%)	⬇️
src/ejabberd_s2s_out.erl	58.12% <0.00%> (-0.23%)	⬇️
src/ejabberd_c2s.erl	89.25% <0.00%> (-0.23%)	⬇️
src/mod_muc_room.erl	77.38% <0.00%> (-0.12%)	⬇️
src/mod_muc_log.erl	77.72% <0.00%> (ø)
... and 8 more

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[chrzaszcz]

Looking good, a few comments from me.

[chrzaszcz]

Looking good! Just a few minor comments.

[chrzaszcz]

Looks good!