more details in JSON API

See #1206, release log:

• f7fb816 by @yegor256: #1206 group by message id
• 54a2850 by @pnatashap: [#1207] fix setup-ruby action
• 5c69ac8 by @pnatashap: [#1207] fix style
• aed2f83 by @pnatashap: [#1207] fix style
• af00e5c by @pnatashap: [#1207] fix codecov run
• 00cae0f by @yegor256: #1206 extra checks
• ee1f653 by @yegor256: #1206 test for search
• 434b13b by @yegor256: #1206 more tests
• bae32cb by @yegor256: #1206 API test
• 06910d2 by @yegor256: #1206 show value

Released by Rultor 2.0-SNAPSHOT, see build log