## **Description**

This PR adds a display of a deprecation warning when a user switches to
MUMBAI network

## **Related issues**

Fixes:

## **Manual testing steps**

1. Go to settings => network => add network => Custom networks
2. Fill in inputs: Name:Mumbai; RPC_URL:https://80001.rpc.thirdweb.com;
chainId: 80001; Symbol: MATIC
3. Switch to this network
4. You should be able to see a deprecation warning "This network is
deprecated"

## **Screenshots/Recordings**

<!-- If applicable, add screenshots and/or recordings to visualize the
before and after of your change. -->

### **Before**


https://github.com/MetaMask/metamask-mobile/assets/10994169/2aac6cf6-b884-4dac-8505-647ce2fabf35




### **After**


https://github.com/MetaMask/metamask-mobile/assets/10994169/1ca57d35-d415-4aa5-b6e8-383973f848cd


## **Pre-merge author checklist**

- [ ] I’ve followed [MetaMask Coding
Standards](https://github.com/MetaMask/metamask-mobile/blob/main/.github/guidelines/CODING_GUIDELINES.md).
- [ ] 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](https://jsdoc.app/) format
if applicable
- [ ] I’ve applied the right labels on the PR (see [labeling
guidelines](https://github.com/MetaMask/metamask-mobile/blob/main/.github/guidelines/LABELING_GUIDELINES.md)).
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.

…mbai