feat: add getAccounts to AccountsController

[hmalik88]

Explanation

Added plural getAccounts method to fetch accounts from a list of account IDs. This method will primarily be used in the multichain accounts service to avoid having to fetch the entire list of accounts and iterating through them.

References

N/A

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, highlighting breaking changes as necessary
• I've prepared draft pull requests for clients and consumer packages to resolve any breaking changes

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Note

Adds plural getAccounts API to AccountsController, with messaging action, tests, and changelog entry.

• AccountsController:
  • Add getAccounts(accountIds: string[]) to return multiple accounts by ID.
  • Define AccountsControllerGetAccountsAction and register AccountsController:getAccounts handler.
• Exports:
  • Export AccountsControllerGetAccountsAction from src/index.ts.
• Tests:
  • Add unit test for getAccounts in AccountsController.test.ts.
• Docs:
  • Update CHANGELOG.md with new method under Unreleased.

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