Resolve implicit function declarations warnings

[pixelboehm]

When compiling, various warnings for implicit function declarations arise as seen below.

app/main.c:113:5: warning: implicit declaration of function 'debugWriteLine' [-Wimplicit-function-declaration]
  113 |     debugWriteLine("Sending Data\r\n");
      |     ^~~~~~~~~~~~~~
app/main.c: In function 'main':
app/main.c:142:5: warning: implicit declaration of function 'led_mcu_init' [-Wimplicit-function-declaration]
  142 |     led_mcu_init();
      |     ^~~~~~~~~~~~
app/main.c:143:5: warning: implicit declaration of function 'debugInit' [-Wimplicit-function-declaration]
  143 |     debugInit(NULL);
      |     ^~~~~~~~~
app/main.c:222:13: warning: implicit declaration of function 'debugReadCharAvailable' [-Wimplicit-function-declaration]
  222 |         if (debugReadCharAvailable())
      |             ^~~~~~~~~~~~~~~~~~~~~~
app/main.c:224:28: warning: implicit declaration of function 'debugGetChar' [-Wimplicit-function-declaration]
  224 |             uint8_t data = debugGetChar();
      |                            ^~~~~~~~~~~~
app/main.c:225:13: warning: implicit declaration of function 'control_handleChar' [-Wimplicit-function-declaration]
  225 |             control_handleChar(data);
      |             ^~~~~~~~~~~~~~~~~~
app/main.c:227:9: warning: implicit declaration of function 'debugTask' [-Wimplicit-function-declaration]
  227 |         debugTask();