feat: add warning banner to custom network bottom sheet

[EtherWizard33]

Description

This small PR adds a banner to the custom network verficition info bottom sheet.
This change is hidden behind the feature flag hiding multichain features.

Related issues

Contributes to solve issue https://github.com/MetaMask/MetaMask-planning/issues/2804

Manual testing steps

from a dapp tab, in the dapp, switch network to a custom network
the bottom sheet seen below will show

Screenshots/Recordings

Before	After

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.

[github-actions]

CLA Signature Action: All authors have signed the CLA. You may need to manually re-run the blocking PR check if it doesn't pass in a few minutes.

[github-actions]

Bitrise

✅✅✅ pr_smoke_e2e_pipeline passed on Bitrise! ✅✅✅

Commit hash: 22aeb2c
Build link: https://app.bitrise.io/app/be69d4368ee7e86d/pipelines/5d698350-33dc-4627-9065-fd8145edd115

Note

• You can kick off another pr_smoke_e2e_pipeline on Bitrise by removing and re-applying the Run Smoke E2E label on the pull request

[sonarcloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
50.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarCloud

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 40.00000% with 3 lines in your changes missing coverage. Please review.

Project coverage is 50.61%. Comparing base (d7586ee) to head (22aeb2c).
Report is 1 commits behind head on main.

Files	Patch %	Lines
...etworkVerificationInfo/NetworkVerificationInfo.tsx	40.00%	2 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #10542      +/-   ##
==========================================
- Coverage   50.61%   50.61%   -0.01%     
==========================================
  Files        1516     1516              
  Lines       36188    36213      +25     
  Branches     4182     4197      +15     
==========================================
+ Hits        18317    18328      +11     
- Misses      16680    16682       +2     
- Partials     1191     1203      +12     

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