Add getAssetMetadata action to MultichainAssetsController

[GuillaumeRx]

Explanation

This adds an action to the MultichainAssetsController called getAssetMetada which allows to get a specific asset Metadata.

This allows us to get a specific metadata without having to pull the entire controller state.

References

• Related to feat: Add AssetSelector snaps#3166

Changelog

@metamask/assets-controller

• ADDED: Add getAssetMetadata action to MultichainAssetsController.

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 highlighted breaking changes using the "BREAKING" category above as appropriate
• I've prepared draft pull requests for clients and consumer packages to resolve any breaking changes