Implement domain removal in mod_offline

[Premwoik]

This PR implements domain removal in mod_roster (only RDBMS). It adds domain removal hook, domain removal callback in the RDBMS module, and test case.

Also: Beautify tests for domain removal from mod_roster.

[mongoose-im]

small_tests_24 / small_tests / 366854d
Reports root / small

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internal_mnesia_24 / internal_mnesia / 366854d
Reports root/ big
OK: 1589 / Failed: 0 / User-skipped: 293 / Auto-skipped: 0

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small_tests_23 / small_tests / 366854d
Reports root / small

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dynamic_domains_24 / pgsql_mnesia / 366854d
Reports root/ big
OK: 2698 / Failed: 0 / User-skipped: 184 / Auto-skipped: 0

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ldap_mnesia_24 / ldap_mnesia / 366854d
Reports root/ big
OK: 1486 / Failed: 0 / User-skipped: 396 / Auto-skipped: 0

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dynamic_domains_23 / pgsql_mnesia / 366854d
Reports root/ big
OK: 2698 / Failed: 0 / User-skipped: 184 / Auto-skipped: 0

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ldap_mnesia_23 / ldap_mnesia / 366854d
Reports root/ big
OK: 1486 / Failed: 0 / User-skipped: 396 / Auto-skipped: 0

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mysql_redis_24 / mysql_redis / 366854d
Reports root/ big
OK: 3050 / Failed: 0 / User-skipped: 228 / Auto-skipped: 0

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pgsql_mnesia_24 / pgsql_mnesia / 366854d
Reports root/ big
OK: 3067 / Failed: 0 / User-skipped: 211 / Auto-skipped: 0

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elasticsearch_and_cassandra_24 / elasticsearch_and_cassandra_mnesia / 366854d
Reports root/ big
OK: 1862 / Failed: 0 / User-skipped: 319 / Auto-skipped: 0

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pgsql_mnesia_23 / pgsql_mnesia / 366854d
Reports root/ big
OK: 3067 / Failed: 0 / User-skipped: 211 / Auto-skipped: 0

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mssql_mnesia_24 / odbc_mssql_mnesia / 366854d
Reports root/ big
OK: 3067 / Failed: 0 / User-skipped: 211 / Auto-skipped: 0

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riak_mnesia_24 / riak_mnesia / 366854d
Reports root/ big
OK: 1709 / Failed: 0 / User-skipped: 322 / Auto-skipped: 0

[codecov]

Codecov Report

Merging #3299 (366854d) into master (def9c13) will increase coverage by 0.09%.
The diff coverage is 85.71%.

@@            Coverage Diff             @@
##           master    #3299      +/-   ##
==========================================
+ Coverage   80.17%   80.26%   +0.09%     
==========================================
  Files         398      398              
  Lines       32577    32584       +7     
==========================================
+ Hits        26120    26155      +35     
+ Misses       6457     6429      -28     

Impacted Files	Coverage Δ
src/offline/mod_offline.erl	77.83% <75.00%> (-0.07%)	⬇️
src/offline/mod_offline_rdbms.erl	94.20% <100.00%> (+0.26%)	⬆️
src/ejabberd.erl	45.00% <0.00%> (-10.00%)	⬇️
...c/global_distrib/mod_global_distrib_server_mgr.erl	74.57% <0.00%> (-2.26%)	⬇️
src/global_distrib/mod_global_distrib_receiver.erl	78.88% <0.00%> (-1.12%)	⬇️
src/mod_roster.erl	78.85% <0.00%> (-0.48%)	⬇️
src/mod_muc.erl	73.76% <0.00%> (-0.23%)	⬇️
src/mod_muc_room.erl	77.12% <0.00%> (-0.06%)	⬇️
src/mod_muc_log.erl	77.88% <0.00%> (ø)
src/ejabberd_c2s.erl	89.29% <0.00%> (+0.07%)	⬆️
... and 13 more

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