Auto merge of #145812 - karolzwolak:attrs-in-fields-and-variants-section, r=GuillaumeGomez

rustdoc: render attributes in Field and Variants sections

Follow up to  rust-lang/rust#145782.
Render attributes in Field and Variants sections.

Associated constants and methods are already rendered with attributes in their sections, so I figured out fields  and variants should too.
(no change here)
<img width="378" height="265" alt="image" src="https://github.com/user-attachments/assets/b4f45c42-0146-486e-8881-138d2a7ad1c4" />
r? `@GuillaumeGomez`

---
Before (left) / after (right):

<img width="396" height="519" alt="image" src="https://github.com/user-attachments/assets/18288e13-09e7-448c-ba98-2023fa6df597" />
<img width="382" height="597" alt="image" src="https://github.com/user-attachments/assets/e624dc84-d169-41cc-bb89-7a1c2b2bb3e3" />

<img width="371" height="313" alt="image" src="https://github.com/user-attachments/assets/29833645-0b93-4900-80a8-c5a1e0b541b4" />
<img width="371" height="331" alt="image" src="https://github.com/user-attachments/assets/d5ce4b9e-f7f1-4f36-8ac0-08b0b5077e48" />

<img width="362" height="309" alt="image" src="https://github.com/user-attachments/assets/0436a51d-29a5-4403-a27c-7697524f807a" />
<img width="357" height="332" alt="image" src="https://github.com/user-attachments/assets/9a759fc5-30e7-4bbb-a88a-a3e3d1ed02aa" />

Author: bors