CustomSelectControl does not prevent keypress events from bubbling up

[opr]

Description

When you click a CustomSelectControl and start typing to move to an item, the event is not cancelled.
This may be related to downshift (potentially relevant PR there, though this is from some time ago: downshift-js/downshift#633)

Step-by-step reproduction instructions

1. Open the storybook for this project: npm run storybook:dev
2. Go to the CustomSelectControl > Default component, click it and start typing s to get to the entry Small
3. Notice the storybook sidebar has closed, due to the s keypress not being cancelled.

Expected behaviour

Keypress events when using the CustomSelectControl should be cancelled before they are handled by other listeners.

Actual behaviour

Keypress events when using the CustomSelectControl are not cancelled before they are handled by other listeners.

Screenshots or screen recording (optional)

https://www.loom.com/share/bbff71315911464c884c15ae8fbf6618

WordPress information

• WordPress version: n/a
• Gutenberg version: trunk
• Are all plugins except Gutenberg deactivated? n/a
• Are you using a default theme (e.g. Twenty Twenty-One)? n/a

Device information

• Device: Desktop
• Operating system: Mac OS Big Sur
• Browser: Brave Version 1.20.110 Chromium: 88.0.4324.192 (Official Build) (x86_64)