[shell] Remove base64 commands

Base64 encoding/decoding is not specific to Matter so base64
shell commands are not useful on actual Matter devices.

Author: Damian-Nordic

src/lib/shell/Commands.h

@@ -20,12 +20,6 @@
 namespace chip {
 namespace Shell {
 
-/**
- * This function registers the base64 encode/decode commands.
- *
- */
-void RegisterBase64Commands();
-
 /**
  * This function registers the BLE commands.
  *

src/lib/shell/Engine.cpp

@@ -105,7 +105,6 @@ CHIP_ERROR Engine::ExecCommand(int argc, char * argv[])
 
 void Engine::RegisterDefaultCommands()
 {
-    RegisterBase64Commands();
     RegisterMetaCommands();
 #if CHIP_DEVICE_CONFIG_ENABLE_CHIPOBLE
     RegisterBLECommands();

src/lib/shell/commands/BUILD.gn

@@ -20,7 +20,6 @@ import("${chip_root}/src/system/system.gni")
 
 source_set("commands") {
   sources = [
-    "Base64.cpp",
     "Help.cpp",
     "Help.h",
     "Meta.cpp",