fix(dns): keep comments intact with zero values of UpdateDNSRecordParams

[favonia]

Description

Calling UpdateDNSRecord with an (almost) zero value of UpdateDNSRecordParams will cause the existing comments to be erased. The solution is straightforward---change the type of the field Comment from string to &string, just like how the field Proxy has the type &bool instead of bool.

Closes #1371.

Has your change been tested?

Yes, but the test must be done against the real server. It is difficult to include a real test in the Go library.

Types of changes

What sort of change does your code introduce/modify?

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have added tests to cover my changes. CAVEAT: A real test can only be done against the real API server, not against the mock server within the Go library.
• All new and existing tests passed.
• This change is using publicly documented in cloudflare/api-schemas
  and relies on stable APIs.

[github-actions]

changelog detected ✅

[jacobbednarz]

did you manually confirm these API calls are working for your use case on the PATCH endpoint? this lgtm

[codecov-commenter]

Codecov Report

Merging #1393 (e465b29) into master (b9ac804) will increase coverage by 0.08%.
Report is 261 commits behind head on master.
The diff coverage is 50.54%.

@@            Coverage Diff             @@
##           master    #1393      +/-   ##
==========================================
+ Coverage   48.33%   48.41%   +0.08%     
==========================================
  Files         133      139       +6     
  Lines       13023    13809     +786     
==========================================
+ Hits         6295     6686     +391     
- Misses       5201     5466     +265     
- Partials     1527     1657     +130     

Files Changed	Coverage Δ
access_audit_log.go	79.31% <ø> (ø)
access_bookmark.go	72.44% <ø> (ø)
access_keys.go	71.42% <ø> (ø)
access_organization.go	53.84% <ø> (ø)
access_service_tokens.go	51.85% <ø> (ø)
account_members.go	65.54% <ø> (ø)
account_roles.go	53.84% <ø> (ø)
accounts.go	50.81% <ø> (ø)
addressing_address_map.go	39.04% <ø> (ø)
addressing_ip_prefix.go	45.45% <ø> (ø)
... and 121 more

... and 1 file with indirect coverage changes

[favonia]

@jacobbednarz Thanks for the reminder. I did the tests about GetDNSRecord, UpdateDNSRecord and ListDNSRecords (but not CreateDNSRecord), and added some comments. (I actually made some mistake but the manual testing got it.) I decided to keep the type of the Comment field in DNSRecord, ListDNSRecordsParams and CreateDNSRecordParams as string (reverting my earlier commit in this PR), only changing that of UpdateDNSRecordParams to &string. The reason is that the server would omit the empty comment field when returning the results. I hope such inconsistency is okay.

[jacobbednarz]

I hope such inconsistency is okay.

it is! and it only that, this is a shining example of where the CRUD operation specific params for a method allow us to make isolated changes without breaking all the method usages at once.

[favonia]

@jacobbednarz Personally I think this is ready to go!

[jacobbednarz]

thank you!

[github-actions]

This functionality has been released in v0.77.0.

For further feature requests or bug reports with this functionality, please create a new GitHub issue following the template. Thank you!