rentEpoch in AccountHeader should be a bigint

[Juici]

rentEpoch return by the RPC is a u64 and should be bigint in AccountHeader in order to not lose precision.

umi/packages/umi/src/Account.ts

Lines 16 to 21 in eda8af5

	export type AccountHeader = {
	executable: boolean;
	owner: PublicKey;
	lamports: SolAmount;
	rentEpoch?: number;
	};

If we call getAccountInfo (on devnet) for the public key (vines1vzrYbzLMRdu58ou5XTby4qAqVRLmqo36NKPTg) in the example for https://docs.solana.com/api/http#getaccountinfo, then the account info returned is:

{
  "data": ["", "base64"],
  "executable": false,
  "lamports": 88819743038050,
  "owner": "11111111111111111111111111111111",
  "rentEpoch": 18446744073709551615,
  "space": 0
}

Here we can see the value for the rentEpoch is 18446744073709551615, however as a number we lose precision and get 18446744073709552000.

[lorisleiva]

Hi 👋 Thanks for reporting this. That's something I've also noticed since working on the new web3.js haha. I'm happy to accept a PR change for this change with a minor changeset.

[HarishPrasannaV]

Hey, I'm a beginner and would like to work on this. Any context and advice are highly appreciated.

[Juici]

Fixed in #105.