rfc: implement Dictionary<T>

[cdaringe]

Is your feature request related to a real problem or use-case?

I frequently need the common type: Dictionary<T = unknown> = Record<string, T>, common for JS objects

Describe a solution including usage in code example

Dictionary<T = unknown> = Record<string, T>

Who does this impact? Who is this for?

All TS users typing Record<string, T> objects, who want a shorthand

Describe alternatives you've considered (optional)

Just use Record<string, ...> everywhere

Additional context (optional)

:)