Simplify hazmat feature docs

[leighmcculloch]

What

Remove hazmat feature from doc cfg attributes, keeping only the specific hazmat-address and hazmat-crypto features in documentation.

Before

After

Why

The generic hazmat feature is used for compilation gating, but really only exists historically for backwards compatibility and as something used for testing during development of the SDK. Generally folks should use the narrower scoped hazmat features, so showing it in documentation guides folks to do the not best practice, which results in enabling more hazmat APIs than are necessary.

[Copilot]

Pull request overview

This PR simplifies the documentation configuration attributes for hazmat features by removing redundant references to the generic hazmat feature, keeping only the specific granular features (hazmat-crypto and hazmat-address). This change guides users toward best practices by exposing only the minimal necessary hazmat APIs in documentation.

• Removes any(feature = "hazmat", feature = "hazmat-crypto") in favor of just feature = "hazmat-crypto" in doc attributes
• Removes any(feature = "hazmat", feature = "hazmat-address") in favor of just feature = "hazmat-address" in doc attributes
• Maintains backward compatibility as the generic hazmat feature still enables all sub-features for compilation

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated no comments.

File	Description
soroban-sdk/src/env.rs	Simplified doc cfg for crypto_hazmat() method to show only hazmat-crypto feature
soroban-sdk/src/crypto.rs	Simplified doc cfg for CryptoHazmat struct to show only hazmat-crypto feature
soroban-sdk/src/address_payload.rs	Simplified module-level doc cfg to show only hazmat-address feature
soroban-sdk/src/address.rs	Simplified doc cfg for to_payload() and from_payload() methods to show only hazmat-address feature