feat: add a histrical wit-bindgen

__wasm/wit-bindgen-sample/wit-bindgen/tests/runtime/variants/exports.wit

@@ -0,0 +1,30 @@
+test-imports: func()
+
+roundtrip-option: func(a: option<float32>) -> option<u8>
+roundtrip-result: func(a: expected<u32, float32>) -> expected<float64, u8>
+
+enum e1 { a, b }
+roundtrip-enum: func(a: e1) -> e1
+
+invert-bool: func(a: bool) -> bool
+
+variant c1 { a(s32), b(s64) }
+variant c2 { a(s32), b(float32) }
+variant c3 { a(s32), b(float64) }
+variant c4 { a(s64), b(float32) }
+variant c5 { a(s64), b(float64) }
+variant c6 { a(float32), b(float64) }
+type casts = tuple<c1, c2, c3, c4, c5, c6>
+variant-casts: func(a: casts) -> casts
+
+variant z1 { a(s32), b }
+variant z2 { a(s64), b }
+variant z3 { a(float32), b }
+variant z4 { a(float64), b }
+type zeros = tuple<z1, z2, z3, z4>
+variant-zeros: func(a: zeros) -> zeros
+
+type option-typedef = option<u32>
+type bool-typedef = bool
+type result-typedef = expected<u32, unit>
+variant-typedefs: func(a: option-typedef, b: bool-typedef, c: result-typedef)