Implement an accessible dialog

[KittyGiraudel]

The current dialog implementation in use when creating a category on the fly when adding a new plant or the one to manage the modules is fundamentally inaccessible. My recommendation would be to create a thin Vue component wrapper a11y-dialog to avoid having to reimplement the underlying logic.

A few things that should happen (most of them done by a11y-dialog):

• [ ] The focus should be moved inside the dialog on open.
• [ ] The focus should be moved back where it was before opening.
• [ ] The focus should be trapped within the dialog.
• [ ] The ESC key should close the dialog.
• [ ] The main content of the page should be hidden from the accessibility tree.
• [ ] The dialog container should be present in the accessibility tree.
• [ ] The dialog should have dialog role in the accessibility tree.
• [ ] The dialog should have an associated name in the accessibility tree.

[morkro]

That's been done with vue-a11y-dialog.