Publish localhost locator if no other locators are avalable or when binding to the localhost interface.

[Hugal31]

This PR does two things:

When listening on an unspecified IP address (i.e. 0.0.0.0 and [::]):

1. If a binding interface is specified, do not filter out localhost addresses. Rational: we'll only get localhost addresses if the bound interface is the loopback interface (at least on Unix systems, someone correct me on Windows?)
2. If the list of IP locator is empty and we didn't specify any interface, manually add a localhost locator.

Note that is has the side effect of adding the localhost locator to the list even if there is already another non-ip locator (e.g. Unix socket, ...). I think that's all-right.

Closes #1989

[github-actions]

PR missing one of the required labels: {'new feature', 'dependencies', 'enhancement', 'breaking-change', 'bug', 'documentation', 'internal'}

[codecov]

Codecov Report

❌ Patch coverage is 90.00000% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 70.85%. Comparing base (392ea49) to head (7f08327).
⚠️ Report is 51 commits behind head on main.

Files with missing lines	Patch %	Lines
commons/zenoh-util/src/net/mod.rs	90.00%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1990      +/-   ##
==========================================
- Coverage   71.02%   70.85%   -0.18%     
==========================================
  Files         365      365              
  Lines       61617    61630      +13     
==========================================
- Hits        43766    43668      -98     
- Misses      17851    17962     +111     

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