Support config domains with either method or attribute domain_name

[jsiirola]

Fixes # .

Summary/Motivation:

This is a follow-on to #3126 where we were defining functor domain validators just to be able to define the domain_name method. This simple fix supports retrieving the domain name as either an attribute, property, or method.

Changes proposed in this PR:

• Support specifying a custom domain name as either a domain_name attribute or method

Legal Acknowledgement

By contributing to this software project, I have read the contribution guide and agree to the following terms and conditions for my contribution:

1. I agree my contributions are submitted under the BSD license.
2. I represent I am authorized to make the contributions and grant the license. If my employer has rights to intellectual property that includes these contributions, I represent that I have received permission to make contributions and grant the required license on behalf of that employer.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (0b4ea7d) 88.38% compared to head (41d8197) 88.37%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3159      +/-   ##
==========================================
- Coverage   88.38%   88.37%   -0.01%     
==========================================
  Files         846      846              
  Lines       94827    94830       +3     
==========================================
- Hits        83811    83806       -5     
- Misses      11016    11024       +8     

Flag	Coverage Δ
linux	86.32% <100.00%> (+<0.01%)	⬆️
osx	75.74% <100.00%> (+<0.01%)	⬆️
other	86.52% <100.00%> (-0.01%)	⬇️
win	83.80% <100.00%> (-0.01%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.