feat: introduce flag validate_user_defined_fields

[Vlad-Bukatin]

closes: #331

[codecov]

Codecov Report

❌ Patch coverage is 94.67593% with 23 lines in your changes missing coverage. Please review.
✅ Project coverage is 91.84%. Comparing base (b8cb424) to head (f8e9b92).

Files with missing lines	Patch %	Lines
crates/hotfix-message/src/builder.rs	93.58%	20 Missing ⚠️
crates/hotfix/src/session.rs	83.33%	3 Missing ⚠️

Additional details and impacted files

@@ Coverage Diff @@## main #352 +/- ##
==========================================
+ Coverage 91.72% 91.84% +0.12% 
==========================================
Files 94 94 Lines 10038 10423 +385 ==========================================
+ Hits 9207 9573 +366 - Misses 831 850 +19 

Flag	Coverage Δ
core	91.75% <94.67%> (+0.12%)	⬆️

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[davidsteiner]

@Vlad-Bukatin sorry, I'll get to this as soon as I can. I just have quite a lot going on, and this change is a bit larger so I want to give it a proper read.

[davidsteiner]

The general direction looks good to me. My only functional concern is how we check the parent groups - left a comment on that.

Also, we're not too strict on test coverage, but I feel like builder.rs has a few interesting branches which aren't covered by any tests. It would be great to add some coverage for those.

Apologies for the very slow review.

[davidsteiner]

If I read this correctly, this checks only the immediate parent. I think this is an issue for any scenario where the next tag isn't one for the enclosing group, but another ancestor - e.g. when an inner group and an outer group end at the same tag, so the next tag is for the message (the outer group's parent). What do you think?

[Vlad-Bukatin]

@davidsteiner Thanks for the review! No worries at all about the delay - I've been quite busy on my end as well.
I'll look into your comment regarding the parent groups logic and update that. I will also add some test coverage (was planning for some time... but didn't have a chance to look into it).

Hopefully I would be able to do it next week

[Vlad-Bukatin]

@davidsteiner took me some time, but I think it is ready