feat: enable duo chat dependencies context category

Description

Enables the Duo Chat context category for adding repo dependencies.

Updates gitlab/ui to include the new UI for the category, and maps the category from LS -> Vue to enable the category.

There is an unrelated change to ensure the chat prompt placeholder text stays the same.

Related Issues

Resolves #1658 (closed)

How has this been tested?

• open Duo Chat, /include, select dependencies for the repo
• ask questions related to the dependencies, ensure response shows this context has been used
• test on project with multiple nested repos (e.g. gitlab-development-kit), ensure each nested repo dependencies can be selected
• when dependencies are selected, click to open details modal and list deps

General testing of gitlab/ui update over webviews

Screenshots (if appropriate)

What CHANGELOG entry will this MR create?

• fix: Bug fix fixes - a user-facing issue in production - included in changelog
• feature: New feature - a user-facing change which adds functionality - included in changelog
• BREAKING CHANGE: (fix or feature that would cause existing functionality to change) - should bump major version, mentioned in the changelog
• None - other non-user-facing changes