Improve readability of Merge result

[papb]

Consider this example:

type Foo = { foo: string };
type Bar = { bar: string };

type Merged = Merge<Foo, Bar>;

Before this PR:

After this PR:

[sindresorhus]

This looks like https://gist.github.com/ClickerMonkey/a081b990b9b14215141fb6248cef4dc4#file-types-ts-L49-L54 Maybe we should do it like that one and call it Simplify? I think it might be useful for other types too, so can you move it to https://github.com/sindresorhus/type-fest/blob/master/source/utilities.d.ts

[sindresorhus]

@mmkal Do you know of any way to test this? To ensure it doesn't regress in the future.

[sindresorhus]

This is blocked by https://github.com/sindresorhus/type-fest/pull/157/files#diff-520a63fe400b4b92fa3ccc14cabc1d84153987354c3f242deddfaeff0a7deae2, which introduces such a type.

[mmkal]

@sindresorhus I can't think of a way to do it without using the compiler API, but maybe that would be appropriate given this library is specifically for types.

[sindresorhus]

@papb Can you update to use https://github.com/sindresorhus/type-fest/blob/master/source/simplify.d.ts ?