[Basemaps] Improve basemaps list in admin

[bruhnild]

List :

• [ ] Add search bar
• [ ] A user can't delete the basemap used in the viewport in order to prevent deleting all basemaps in the app
• [ ] Drop edit button in list (edition is done by click on row)
• [ ] Add a Ranking field to sort and see in which order views are display in front-ed

Detail / edit :

• [ ] Be able to preview basemap from creation step
• [ ] Override attribution, glyphs and sprites if defined