feat(typescript-types): Add IsUnknown<T>

packages/typescript-types/src/is-unknown.ts

@@ -0,0 +1,9 @@
+import type { If } from './if.js'
+import type { IsAny } from './is-any.js'
+import type { IsNever } from './is-never.js'
+
+export type IsUnknown<T> = If<
+	IsAny<T>,
+	false,
+	If<IsNever<T>, false, T extends unknown ? (unknown extends T ? true : false) : false>
+>