feat: implement enableAllPopularNetworks function with comprehensive … (MetaMask#6367)

…tests

## Explanation

This PR implements 

- the `enableAllPopularNetworks()` to enable all popular networks
- modifies the `enableNetwork()` function to use exclusive behavior,
ensuring only one network is enabled per namespace at a time.

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## References

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## Checklist

- [ ] I've updated the test suite for new or updated code as appropriate
- [ ] I've updated documentation (JSDoc, Markdown, etc.) for new or
updated code as appropriate
- [ ] I've communicated my changes to consumers by [updating changelogs
for packages I've
changed](https://github.com/MetaMask/core/tree/main/docs/contributing.md#updating-changelogs),
highlighting breaking changes as necessary
- [ ] I've prepared draft pull requests for clients and consumer
packages to resolve any breaking changes

Author: salimtb

packages/network-enablement-controller/CHANGELOG.md

@@ -7,8 +7,13 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Added
+
+- Add `enableAllPopularNetworks()` method to enable all popular networks and Solana mainnet simultaneously ([#6367](https://github.com/MetaMask/core/pull/6367))
+
 ### Changed
 
+- **BREAKING:** `enableNetwork()` now implements exclusive behavior - disables all other networks in the same namespace before enabling the target network ([#6367](https://github.com/MetaMask/core/pull/6367))
 - Bump `@metamask/base-controller` from `^8.1.0` to `^8.2.0` ([#6355](https://github.com/MetaMask/core/pull/6355))
 
 ## [0.3.0]