fix(core): mobile menu not closing and isMobile state not always being correct

[nentor]

Description

This PR fixes a bug where the mobile menu wouldn't close upon route transition. It also fixes a bug where the "isMobile" state of the AppHeader component was not always correct.

Related Issue

Motivation and Context

How Has This Been Tested?

Screenshots:

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• I have read the CONTRIBUTING document.

Changelog

• I have updated the Changelog (V1) v2 and mentioned all breaking changes in the public API.
• I have documented all new public APIs and made changes to existing docs mentioning the parts I've changed so they're up to date.

Tests

• I have written test cases for my code
• I have tested my Pull Request on production build and (to my knowledge) it works without any issues
• I have added tests to cover my changes.
• All new and existing tests passed.

I tested manually my code, and it works well with both:

• Default Theme
• Capybara Theme

Code standards

• My code follows the code style of this project.

• I have followed naming conventions

Docs

• My change requires a change to the documentation.
• I have updated the documentation accordingly.