This commit adds RR DNS support for multimaster mode

[gczuczy]

What does this PR do?

For multimaster mode this commit adds RR DNS support. SRV records are not supported by this PR currently, as SRVs don't make sense in multimaster mode, only with master_type==failover.

What issues does this PR fix or reference?

Fixes: All the issues which mentioned RR DNS support for multimaster mode. SRV is doesn't make sense for multimaster mode, so it's not addressed in this commit.

Previous Behavior

If the masters specified by a hostname were a round-robin DNS record, only the first resolved entry was returned and handled as the master address, the rest ignored.

New Behavior

With master_type==str (multimaster mode), a simple round-robin DNS record (or multiples, in case masters is a list) can be utilized to maintain the lost of masters. This way the list of masters can be maintained in the DNS subsystem in multimaster mode, and changes are not affecting the default minion configuration in the deployment.

Merge requirements satisfied?

[NOTICE] Bug fixes or features added to Salt require tests.

• [x] Docs
• [x] Changelog - https://docs.saltproject.io/en/master/topics/development/changelog.html
• [ ] Tests written/updated

I would like to ask for help regarding the docs/changelog and tests.

Commits signed with GPG?

No

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[gczuczy]

Should I expose the dns_resolve_addresses (salt.utils.network:2157) function to jinja? I think it might be a good idea to do so, it can come useful in reasonable situations writing state files.

[dwoz]

Closing this due to inactivity. Anyone should feel free to re-open it if they want to see it through to the end in one release cycle.

@gczuczy If this is something you want to get into 3008.x please re-open and remove the draft state. Thanks.