0.28.0 Dcaas CLI, MRS SDK and CLI, SDK dcaas direct connection endpoint group, bug fixes

What's Changed

• [CBR] [CLI] Fix 'associate' operation for vault by @Polina-Gubina (#302)
• [CBR] [SDK] fix Mappings parameter in restore backup by @Polina-Gubina (#297)
• [DCAAS] [CLI] Virtual gateway, endpoint group and connection by @irina-pereiaslavskaia ( #296)
• [DCAAS] [SDK] Direct connection endpoint group by @irina-pereiaslavskaia ( #295 )
• [DCAAS] [CLI] Virtual gateway by @irina-pereiaslavskaia (#294)
• [MRS] Implementation of sdk and cli part 1 by @anton-sidelnikov ( #293 )
• [DCAAS] [CLI] Connection by @irina-pereiaslavskaia (#291)
• [CTS] functional tests by @anton-sidelnikov (#194)

Full Changelog: 0.27.0...0.28.0