feat: show back button for settings inner page on extended mode (#37486)

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## **Description**
This PR adds back button to inner pages inside settings.

Some pages in Settings have inner pages like
- Contacts > View/Edit contact
- Security & privacy > Backup SRP
- Security & privacy > Change password
- Transaction shield > Claims Add/View/List 

Currently there is no way to go back to prev pages on `extended mode`.
User has to click on the left menu again or go back from the start every
time.

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## **Changelog**

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CHANGELOG entry: Add back button to Settings inner pages

## **Related issues**

Fixes:

## **Manual testing steps**

1. Login to metamask and make sure you are in `extended mode`
2. Browse Menu > Settings
3. Explore pages like Contact, Security Settings (Backup SRP, Change
password), and Transaction Shield (needs subscription)
4. There should be back button on each inner pages. The back route
should be same with the redirections on popup mode.

## **Screenshots/Recordings**

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### **Before**

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### **After**


https://github.com/user-attachments/assets/3cb3bbd0-ad42-4792-a91f-6a9cc885ab20


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## **Pre-merge author checklist**

- [x] I've followed [MetaMask Contributor
Docs](https://github.com/MetaMask/contributor-docs) and [MetaMask
Extension Coding
Standards](https://github.com/MetaMask/metamask-extension/blob/main/.github/guidelines/CODING_GUIDELINES.md).
- [x] I've completed the PR template to the best of my ability
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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.

<!-- CURSOR_SUMMARY -->
---

> [!NOTE]
> Adds a back button to the settings subheader for inner pages and wires
`backRoute`/`navigate` to handle navigation.
> 
> - **Settings UI (`ui/pages/settings/settings.component.js`)**
> - Add subheader back button on inner pages: renders `ButtonIcon` with
`IconName.ArrowLeft` when `backRoute !==
> `SETTINGS_ROUTE` and not on `NETWORKS_ROUTE`; clicking navigates to
`backRoute`.
> - Props: include `backRoute` and `navigate` (PropTypes updated) to
support back navigation.
> 
> <sup>Written by [Cursor
Bugbot](https://cursor.com/dashboard?tab=bugbot) for commit
4bd2a55. This will update automatically
on new commits. Configure
[here](https://cursor.com/dashboard?tab=bugbot).</sup>
<!-- /CURSOR_SUMMARY -->

Author: lionellbriones

ui/pages/settings/settings.component.js

@@ -323,6 +323,8 @@ class SettingsPage extends PureComponent {
       isAddressEntryPage,
       pathnameI18nKey,
       addressName,
+      backRoute,
+      navigate,
     } = this.props;
     let subheaderText;
 
@@ -334,6 +336,9 @@ class SettingsPage extends PureComponent {
       subheaderText = t(pathnameI18nKey || 'general');
     }
 
+    // Show back button only on inner pages of the settings page
+    const showBackButton = backRoute !== SETTINGS_ROUTE;
+
     return (
       !currentPath.startsWith(NETWORKS_ROUTE) && (
         <Box
@@ -345,6 +350,14 @@ class SettingsPage extends PureComponent {
           flexDirection={FlexDirection.Row}
           alignItems={AlignItems.center}
         >
+          {showBackButton && (
+            <ButtonIcon
+              iconName={IconName.ArrowLeft}
+              onClick={() => navigate(backRoute)}
+              marginRight={2}
+              size={ButtonIconSize.Md}
+            />
+          )}
           <Text variant={TextVariant.headingSm}>{subheaderText}</Text>
           {isAddressEntryPage && (
             <div className="settings-page__subheader--break">