feat(types): Add custom variant to AttachmentType

[tobias-wilfert]

We would like to be able to send a custom attachment type, this makes it such that this is possible.

[github-actions]

	Messages
📖	Do not forget to update Sentry-docs with your feature once the pull request gets approved.

Generated by 🚫 dangerJS against 42033ae

[Copilot]

Pull Request Overview

This PR adds support for custom attachment types by extending the AttachmentType enum to include arbitrary string values. This allows users to send attachments with custom type identifiers beyond the predefined Sentry attachment types.

• Adds a Custom(String) variant to the AttachmentType enum
• Updates the as_str method to work with borrowed values and handle custom types
• Includes deserialization tests for the new custom attachment functionality

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[Copilot]

Removing Copy trait from the enum will impact performance for small operations. Consider keeping Copy and use Cow<'static, str> for the Custom variant to maintain zero-cost abstractions for predefined types while supporting custom strings.

[Copilot]

Unnecessary clone operation. Since as_str now takes &self, you can use self.ty.as_ref().unwrap_or(&AttachmentType::default()).as_str() to avoid cloning the attachment type.

Suggested change

	at = self.ty.clone().unwrap_or_default().as_str(),
	at = self.ty.as_ref().unwrap_or(&AttachmentType::default()).as_str(),

[Swatinem]

maybe a .as_ref().map(|a| a.as_str()).unwrap_or_default() would be even more concise (and avoid the clone).

[tobias-wilfert]

This .as_ref().map(|a| a.as_str()).unwrap_or_default() will yield and empty str rather than event.attachment so not sure we want to change this (at least in this PR).

[tobias-wilfert]

I can still do the explicit unwrap_or though that one should work.

[codecov]

Codecov Report

❌ Patch coverage is 92.30769% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 73.79%. Comparing base (34b27b5) to head (42033ae).
⚠️ Report is 1 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #916      +/-   ##
==========================================
+ Coverage   73.76%   73.79%   +0.02%     
==========================================
  Files          64       64              
  Lines        7533     7544      +11     
==========================================
+ Hits         5557     5567      +10     
- Misses       1976     1977       +1     

[Swatinem]

maybe a .as_ref().map(|a| a.as_str()).unwrap_or_default() would be even more concise (and avoid the clone).