Explore mapping C# spaces to ES modules

[elringus]

Currently, all the bindings and associated types from the C# solution are dumped to a single file (index.mjs and bindings.g.d.ts) and are grouped via TypeScript namespaces. This is sub-optimal for both the DX and performance.

For DX it's preferable to group the exports under sub-modules instead of TypeScript namespaces, so that they can be imported in a more granular way, eg:

import { doX } from "bootsharp/sharp-space-a";
import { doY } from "bootsharp/sharp-space-b";

doX();
doY();

— instead of the current:

import { SharpSpaceA, SharpSpaceB } from "bootsharp";

SharpSpaceA.doX();
SharpSpaceB.doY();

Additionally, TypeScript namespaces usage is generally discouraged in favor of ES modules.

For performance, TypeScript compilers and linters prefer multiple smaller declaration files instead of a single large one. This also benefits tree shaking.