Improve accessibility of toolbar buttons

[putnokiabel]

Description

The buttons in the toolbar are currently not accessible and not labeled correctly when using screen readers (e.g. VoiceOver). This is due to not using the tooltip value on the underlying IconButton from Material.

Changes:

• Allow passing through the tooltip value to the underlying button in ToggleStyleButton (so it's accessible in semantics / VoiceOver)
• Set the correct tooltip value in SelectHeaderStyleButtons. The current approach only allows for setting a single tooltip (same across all header style buttons) which is obviously useless for blind users. This PR fixes this by setting the tooltip to the value displayed on the button (N, H1, H2, etc).

How to test:

Run an app with a toolbar via Xcode, then tap Xcode -> Open developer tool -> Accessibility, and verify that on main, the toolbar buttons don't have tooltips (regardless of tooltips set in ButtonOptions).
With this PR, the user of the plugin can set tooltips via the various ButtonOptions.

Type of Change

• ✨ Feature: New functionality without breaking existing features.
• 🛠️ Bug fix: Resolves an issue without altering current behavior.
• 🧹 Refactor: Code reorganization, no behavior change.
• ❌ Breaking: Alters existing functionality and requires updates.
• 🧪 Tests: New or modified tests
• 📝 Documentation: Updates or additions to documentation.
• 🗑️ Chore: Routine tasks, or maintenance.
• ✅ Build configuration change: Build/configuration changes.