Accessibility - Hamburger menu is missing a label

### Current Behavior

Hamburger menu is missing a label describing it’s purpose to screen readers

### Proposed Behavior

Add label to the hamburger menu describing its purpose e.g "Toggle navigation menu"

### Checklist

- [x] I have read and understand the [contributing guidelines](https://github.com/DependencyTrack/dependency-track/blob/master/CONTRIBUTING.md#filing-issues)
- [x] I have checked the [existing issues](https://github.com/DependencyTrack/frontend/issues) for whether this enhancement was already requested

Start by locating the frontend component that renders the hamburger menu and inspect its current accessible attributes. Done means the control has a purpose-describing label, such as "Toggle navigation menu," that is available to screen readers; no specific file or test is named in the issue.

Written by the indexing model from the issue text.