Function getKeyHandlersForKeyStores

getKeyHandlersForKeyStores(
    connection: Connection,
    accountId: Buffer,
    keyStores: KeyStore[],
): Promise<KeyHandler[]>
Converts a list of keystores into a list of key handlers
Parameters
- connection: Connection
  connection to the blockchain of interest
- accountId: Buffer
  the id of the account of which the key handlers should be valid
- keyStores: KeyStore[]
  the key stores to convert to key handlers
Returns Promise<KeyHandler[]>
a list of ket handlers