[0.74.1] Cherry-pick Hermes atob padding fix

[hirbod]

Target Branch(es)

0.74

Link to commit or PR to be picked

facebook/hermes#1379

Description

base64 decoding fails if the provided string does not contain padding. This is breaking our app.
As a workaround I added following function to add padding before trying to decode.

function ensureBase64Padding(base64: string) {
    const paddingNeeded = (4 - base64.length % 4) % 4;
    return base64 + '='.repeat(paddingNeeded);
}

Kindly asking to cherry-pick this fix.