Allow to specify balance in dry-run

[davidyuk]

aepp-sdk-js/src/chain.ts

Line 379 in 428ebe6

.map((pubKey) => ({ pubKey, amount: DRY_RUN_ACCOUNT.amount })),

Currently, it is set to the maximum value, but the ability to specify the balance can be used to check if the account has enough ae. It was requested by SW.