[RTC-405] Resolve FQDNs in DNS cluster strategy

[mickel8]

After this PR:

• a default node name is jellyfish@(hostname) - thanks to this, when using DNS strategy in docker we don't have to set JF_DIST_NODE_NAME explicitly
• if hostname in node name in DNS strategy is not an ip address, we will try to resolve it under the hood
• JF_DIST_MODE is snam by default - that's because of default node name
• when JF_DIST_ENABLED is set, we always start the node in Elixir code. This means that if we make a release and we want to connect to already running node, we have to use RELEASE env vars i.e.

RELEASE_NODE=<JF_DIST_NODE_NAME(resolved in case of DNS)> RELEASE_COOKIE= RELEASE_DISTRIBUTION= _build/../jellyfish remote

To be precise, not always all of the above ones but this is quite tricky to describe

Documentation update jellyfish-dev/jellyfish-docs#72

Acknowledging the stipulations set forth:

• [x] I hereby confirm that a Pull Request involving updates to the Software Development Kit (SDK) has been smoothly merged, currently awaits processing, or is otherwise deemed unnecessary in this context.
• [x] I also affirm that another Pull Request, specifically addressing updates to the documentation body (commonly referred to as 'docs'), has either been successfully incorporated, is in the process of review, or is considered superfluous under the prevailing circumstances.

[codecov[bot]]

Codecov Report

Merging #137 (e0e8a55) into main (966ac7d) will decrease coverage by 0.09%. Report is 1 commits behind head on main. The diff coverage is 85.18%.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #137 +/- ## ========================================== - Coverage 87.21% 87.12% -0.09% ========================================== Files 60 60 Lines 1087 1103 +16 ========================================== + Hits 948 961 +13 - Misses 139 142 +3 ``` | [Files](https://app.codecov.io/gh/jellyfish-dev/jellyfish/pull/137?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=jellyfish-dev) | Coverage Δ | | |---|---|---| | [lib/jellyfish/application.ex](https://app.codecov.io/gh/jellyfish-dev/jellyfish/pull/137?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=jellyfish-dev#diff-bGliL2plbGx5ZmlzaC9hcHBsaWNhdGlvbi5leA==) | `50.00% <0.00%> (ø)` | | | [lib/jellyfish/config\_reader.ex](https://app.codecov.io/gh/jellyfish-dev/jellyfish/pull/137?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=jellyfish-dev#diff-bGliL2plbGx5ZmlzaC9jb25maWdfcmVhZGVyLmV4) | `93.61% <88.46%> (-2.54%)` | :arrow_down: | ------ [Continue to review full report in Codecov by Sentry](https://app.codecov.io/gh/jellyfish-dev/jellyfish/pull/137?src=pr&el=continue&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=jellyfish-dev). > **Legend** - [Click here to learn more](https://docs.codecov.io/docs/codecov-delta?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=jellyfish-dev) > `Δ = absolute (impact)`, `ø = not affected`, `? = missing data` > Powered by [Codecov](https://app.codecov.io/gh/jellyfish-dev/jellyfish/pull/137?src=pr&el=footer&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=jellyfish-dev). Last update [966ac7d...e0e8a55](https://app.codecov.io/gh/jellyfish-dev/jellyfish/pull/137?src=pr&el=lastupdated&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=jellyfish-dev). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=jellyfish-dev).