feature(unlock-app): Supporting picking lock when doing airdrops

[julien51]

Description

The event UI supports having multiple locks per event. We let the airdrop drawer be used with multiple locks.
There is also a small refactor of the UI to make things a bit less "big".

Checklist:

• 1 PR, 1 purpose: my Pull Request applies to a single purpose
• I have commented my code, particularly in hard-to-understand areas
• I have updated the docs to reflect my changes if applicable
• I have added tests (and stories for frontend components) that prove my fix is effective or that my feature works
• I have performed a self-review of my own code
• If my code involves visual changes, I am adding applicable screenshots to this thread

Release Note Draft Snippet

[julien51]

Fixes #13216

[clemsos]

Lg