feat: Temp search, do not merge

[EtherWizard33]

Description

Adding search to the network bottomsheet as part of the networks management UI redesign. Here is a 2 minute overview demo: https://www.loom.com/share/dc29313a5cd34e9893c76a0caeba0fc1

Here is a link to the related Figma that includes the adding of the search box to the bottom sheet: https://www.figma.com/design/76R5BvAVubUhWaN2Ld7MAv/Default-Networks?node-id=1303-9439&t=yhxfHHCsG0CimP0w-0

Related issues

Fixes: https://github.com/MetaMask/MetaMask-planning/issues/2495

Manual testing steps

1. Add a the following env var that will be used as a feature flag to enable to the feature export MM_NETWORK_UI_REDESIGN_ENABLED="1"
2. From the header in the home screen, click the network selector
3. The network bottom sheet should come up and you should see the search box
4. Type ava in the search box and it should filter out all other networks and show only avalanche
5. For a demo please see the video in the description above

Screenshots/Recordings

Before

After

Pre-merge author checklist

• [ ] I’ve followed MetaMask Contributor Docs and MetaMask Mobile Coding Standards.
• [ ] I've completed the PR template to the best of my ability
• [ ] I’ve included tests if applicable
• [ ] I’ve documented my code using JSDoc format if applicable
• [ ] I’ve applied the right labels on the PR (see labeling guidelines). Not required for external contributors.

Pre-merge reviewer checklist

• [ ] I've manually tested the PR (e.g. pull and build branch, run the app, test code being changed).
• [ ] I confirm that this PR addresses all acceptance criteria described in the ticket it closes and includes the necessary testing evidence such as recordings and or screenshots.

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