[FEATURE] Support Ephemeral dashboards on the UI

[AntoineThebaud]

Description

Add the display of Ephemeral dashboards on the UI.

• the new tab on the project view is not displayed if there are no ephemeral dashboards registered.
• updating the TTL is possible from the project view, not the dashboard view. It's a design choice but there also a technical constraint (aka code genericity) preventing to allow modifying it from the JSON view in the current state.

NB: I made my best to share as much code as possible between Dashboards & Ephemeral Dashboards, I especially wanted to keep a single store & context for dashboards. It may still have room for improvement.

NB: Planned for later: add an option on the new duplicate action to make a dashboard copy ephemeral.

Ref issue #1729.

Screenshots

Checklist

• Pull request has a descriptive title and context useful to a reviewer.
• Pull request title follows the [<catalog_entry>] <commit message> naming convention using one of the
  following catalog_entry values: FEATURE, ENHANCEMENT, BUGFIX, BREAKINGCHANGE, DOC,IGNORE.
• All commits have DCO signoffs.

UI Changes

• Changes that impact the UI include screenshots and/or screencasts of the relevant changes.
• Code follows the UI guidelines.
• Visual tests are stable and unlikely to be flaky.
  See Storybook
  and e2e docs for more details. Common issues
  include:
  • Is the data inconsistent? You need to mock API requests.
  • Does the time change? You need to use consistent time values or mock time utilities.
  • Does it have loading states? You need to wait for loading to complete.

[Nexucis]

noice !