[201_2769] Add accessible property to bibliography drd-props

[Gitjay11]

Fixes #2769

What

Added accessible|3 to bibliography and accessible|4 to bibliography*
in their drd-props definitions in TeXmacs/packages/section/section-base.ts

Why

Users cannot navigate into the bibliography body using the right arrow key

In TeXmacs, the accessible property in drd-props controls whether cursor
navigation via arrow keys can enter a tag's child argument. The bibliography
tag's body is at argument index 3, and bibliography*'s body is at index 4 —
neither had the accessible property set, so the cursor would skip over them entirely.

How

Following the same pattern used by other tags in the codebase (e.g., mini-paragraph
with accessible|1, arrow-with-text with accessible|2), so I added the accessible
property pointing to the body argument index in each tag's drd-props declaration.

[Gitjay11]

hii @da-liii @JackYansongLi , When you have time, please review this PR and let me know if any changes are needed, I would be happy to change. Thank you.