[lib][console] rename some console command types to be prefixed with console_

Some of the structures, notably 'cmd', in the lib console stuff are a
little too generically named and have collided with some other code
so prefix the names a bit more cleanly with console_

The change is largely mechanical, and folks with out of tree code can
easily switch by renaming:
cmd -> console_cmd
cmd_args -> console_cmd_args
cmd_block -> console_cmd_block
console_cmd -> console_cmd_func

Apologies if this breaks you but it should be pretty easy to fix.

app/loader/loader.c

@@ -127,7 +127,7 @@ int tftp_callback(void *data, size_t len, void *arg) {
     return 0;
 }
 
-static int loader(int argc, const cmd_args *argv) {
+static int loader(int argc, const console_cmd_args *argv) {
     static int any_slot = 0;
     static int elf_slot = 1;