breaking: Update domains client to use v4 of API

[olexandr-mazepa]

closes #429

This PR includes the following changes:

• Removed DomainShortData type, because there is no difference between DomainShortData and DomainData in the new version.
• created_at is now a Date object instead of a string in the TDomain type.
• The query type for the domains.list method was extended by state, sort, authority, and search properties.
• The domains.get method was extended, and now allows query.
• Fixed getConnection method to return data instead of undefined.
• getIps, assignIp, deleteIp, linkIpPool, unlinkIpPoll, and updateWebPrefix methods in the DomainClient have been deprecated.
• domains.updateDKIMSelector response shape is changed from { body: { message: 'DKIM selector changed' }, status: 200 } to {message: 'DKIM selector changed', status: 200 }