mjs extension support

[mysuf]

I decided to go mjs way instead of type: module, but umzug can't handle these files atm.

require doesn't work with esm so then maybe it would be nice to make resolver async so I can handle these files with dynamic import.

Now I made it work like this:

		resolve: ({ name, path, context }) => {
			return {
				// adjust the parameters Umzug will
				// pass to migration methods when called
				name,
				up: async () => {
					const { up } = await import(path);
					return up({ context });
				},
				down: async () => {
					const { down } = await import(path);
					return down({ context });
				},
			};
		},

Thanks

[mmkal]

Closing in favour of #608