Add something like `Promise.allKeyed` and `Promise.allSettledKeyed` to `@std/async`

[lionel-rowe]

Is your feature request related to a problem? Please describe.

Add something like Promise.allKeyed/Promise.allSettledKeyed to @std/async, which is more ergonomic than all/allSettled for many use cases.

Per Await dictionary of Promises proposal § Motivation:

• await on individual properties creates a waterfall, rather than running requests in parallel
• Promise.all helps, but is based on order, rather than names, which could lead to mixups
• Solutions using existing syntax can be verbose and pollute the number of variables in scope

Prior art:

• Await dictionary of Promises proposal
• promise-all-properties package

Describe the solution you'd like

Something like this:

type Promises<T extends Record<string, unknown>> = {
    [P in keyof T]: Promise<T[P]> | T[P]
}
type PromisesSettled<T extends Record<string, unknown>> = {
    [P in keyof T]: PromiseSettledResult<T[P]>
}

export declare function promiseAllKeyed<T extends Record<string, unknown>>(
    promises: Promises<T>,
): Promise<T>

export function promiseAllSettledKeyed<T extends Record<string, unknown>>(
    promises: Promises<T>,
): Promise<PromisesSettled<T>>

Describe alternatives you've considered

Naming — promiseAllKeyed? promiseAllProperties? promiseHash? promiseObj? etc.