Generalize QS8 VADD[C] templates to cover QU8 VADD[C] microkernels

- QU8 VADD[C] SSE2 MUL16 microkernels
- QU8 VADD[C] NEON microkernels
- QU8 VADD[C] WAsm SIMD microkernels
- QU8 VADD[C] scalar microkernels
- Unit tests

PiperOrigin-RevId: 385931044
diff --git a/src/qu8-vadd/gen/minmax-scalar-x1.c b/src/qu8-vadd/gen/minmax-scalar-x1.c
new file mode 100644
index 0000000..a2684e0
--- /dev/null
+++ b/src/qu8-vadd/gen/minmax-scalar-x1.c
@@ -0,0 +1,44 @@
+// Auto-generated file. Do not edit!
+//   Template: src/qs8-vadd/scalar.c.in
+//   Generator: tools/xngen
+//
+// Copyright 2021 Google LLC
+//
+// This source code is licensed under the BSD-style license found in the
+// LICENSE file in the root directory of this source tree.
+
+#include <assert.h>
+
+#include <xnnpack/math.h>
+#include <xnnpack/vadd.h>
+
+
+void xnn_qu8_vadd_minmax_ukernel__scalar_x1(
+    size_t n,
+    const uint8_t* input_a,
+    const uint8_t* input_b,
+    uint8_t* output,
+    const union xnn_qu8_add_minmax_params params[restrict XNN_MIN_ELEMENTS(1)]) XNN_DISABLE_TSAN
+{
+  const int32_t vbias = params->scalar.bias;
+  const int32_t va_multiplier = params->scalar.a_multiplier;
+  const int32_t vb_multiplier = params->scalar.b_multiplier;
+  const int32_t vrounding = params->scalar.rounding;
+  const uint32_t vshift = params->scalar.shift;
+  const int32_t voutput_min_less_zero_point = params->scalar.output_min_less_zero_point;
+  const int32_t voutput_max_less_zero_point = params->scalar.output_max_less_zero_point;
+  const int32_t voutput_zero_point = params->scalar.output_zero_point;
+
+  do {
+    const int32_t va = *input_a++;
+    const int32_t vb = *input_b++;
+    const int32_t vacc = vbias + va * va_multiplier + vb * vb_multiplier;
+
+    int32_t vout = asr_s32(vacc + vrounding, vshift);
+    vout = math_max_s32(vout, voutput_min_less_zero_point);
+    vout = math_min_s32(vout, voutput_max_less_zero_point);
+    *output++ = (uint8_t) (vout + voutput_zero_point);
+
+    n -= sizeof(uint8_t);
+  } while (n != 0);
+}