Replace Buffer with Uint8Array

[xcaptain]

I'm developing a dapp using sveltekit + tonconnectui, I have to install the vite-plugin-node-polyfills package to fix the Fix Buffer is not defined error, because @ton/core uses Buffer which is a nodejs only type. I hope you can replace it with Uint8Array so we can better use it in browser.

An example can be found at: https://github.com/ton-org/ton-core/blob/main/src/boc/BitString.ts#L17

[xcaptain]

@dvlkv can you take a look at it? do you have any plan to remove nodejs dependency?

[dvlkv]

Yes we do have plans removing Buffer in the next major version. However, I cannot provide you any estimates on this update.

[xcaptain]

This PR shows it's not hard to replace Buffer with Uint8Array. I'm happy to help if you need.