Export formats separately, without scoping

[o-alexandrov]

Related issues

• Take into account ajv code.esm option #68

By scoping formats into fullFormats and fastFormats:

• it's harder to do code generation as it's impossible to import a format in a single line
• it makes it more complicated not to have multiple imports of the same variable

As a breaking change proposal, let's export two modules instead:

• formats-fast.js
• formats-full.js

This way, when doing code generation, it'd be possible to have a single line import:

import { int32 } from "ajv-formats/dist/formats-full"