Proper handling of SetApplicationCpuTimeLimit with invalid parameters (#353)

* Add NotImplemented error code

* Add proper handling of SetAppCpuTimeLimit with invalid params

Set default time limit to 0

* Add AppCpuTimeLimit tests

* Replace spaces with tab

tests/AppCpuTimeLimit/source/main.c

@@ -0,0 +1,55 @@
+#include <3ds.h>
+
+#include <stdio.h>
+
+int main(int argc, char **argv) {
+    gfxInitDefault();
+
+    consoleInit(GFX_TOP, NULL);
+
+    printf("--- APT::SetAppCpuTimeLimit ---\n\n");
+
+    // Get initial percentage
+    u32 percentage;
+    APT_GetAppCpuTimeLimit(&percentage);
+
+    printf("Initial percentage: %lu\n\n", percentage);
+
+    // Try all percentages from 0-100%, print failed calls
+    for (int i = 0; i <= 100; i++) {
+        const Result res = APT_SetAppCpuTimeLimit(i);
+
+        if (R_FAILED(res)) {
+            APT_GetAppCpuTimeLimit(&percentage);
+
+            printf("[%d:%lu:%lX]\n", i, percentage, res);
+        }
+    }
+
+    // Send command with invalid fixed value
+    u32 aptcmdbuf[16];
+    aptcmdbuf[0] = 0x004F0080;
+    aptcmdbuf[1] = 0;
+    aptcmdbuf[2] = 20;
+
+    aptSendCommand(aptcmdbuf);
+
+    printf("\nWith fixed = 0: [%08lX:%08lX]\n", aptcmdbuf[0], aptcmdbuf[1]);
+
+    while (aptMainLoop()) {
+        hidScanInput();
+
+        if ((hidKeysDown() & KEY_START) != 0) {
+            break;
+        }
+
+        gfxFlushBuffers();
+        gfxSwapBuffers();
+
+        gspWaitForVBlank();
+    }
+
+    gfxExit();
+
+    return 0;
+}