Helper function to rename the keys in a record from Foo.bar → fooBar

The data returned from Cube is an array of objects, whose keys are dimension and measure names. However, these keys are not JavaScript identifiers, which makes them awkward to work with:

```ts
const query = {
dimensions: ["Item.name"],
measures: ["Sale.count"],
} as const;

const record = (await api.load(query)).rawData()[0];

const name = record["Item.name"];
const count = record["Sale.count"];
```

To make this easier, I've written a helper function, `camelizeRecord`, that rewrites the key names:

```ts
const record = (await api.load(query)).rawData().map(camelizeRecord)[0];

const name = record.itemName;
const count = record.saleCount;
```

The function is type safe, so if the type of `record` is inferred to be `{ "Site.name": string | number | boolean | null, "Sale.count": string | number | boolean | null }` (as it is with #4446), then the type of `camelizeRecord(record)` will be inferred to be `{ "siteName": string | number | boolean | null, "saleCount": string | number | boolean | null }`.

The implementation is straightforward and about 20 LOC.

After having tried this out for a couple weeks, I can confirm that my teammates and I find it very useful. It's a minor ergonomic improvement, but it adds up, and the code looks much nicer. I think it would be worth adding to `@cubejs-client/core`.