Warn the user when Zebra doesn't recognize the format of zebrad.toml

[upbqdn]

Motivation

When the format of zebrad.toml changes, Zebra doesn't recognize it appropriately and returns an unclear error saying that it couldn't read some data. This becomes an issue when users install a new version of Zebra that uses a new format of zebrad.toml, but keep their old zebrad.toml file.

Solution

Zebra now provides a message saying that it could not parse the provided config file, and suggests that the user might be using a deprecated format of the file.

Close #4665

Reviewer Checklist

• Tests for Expected Behaviour

[codecov]

Codecov Report

Merging #4689 (7465d78) into main (e709420) will increase coverage by 0.08%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main    #4689      +/-   ##
==========================================
+ Coverage   78.83%   78.92%   +0.08%     
==========================================
  Files         304      304              
  Lines       37506    37508       +2     
==========================================
+ Hits        29568    29602      +34     
+ Misses       7938     7906      -32     

[teor2345]

Looks good!

I did a merge with PR #4676 and added some comments.

[teor2345]

Thanks for the quick fixes!