The new command requires the toolchain binary path to exist in the file system before building using a toolchain (to handle the case where gba-dev is uninstalled but $(DEVKITARM) still exists))
Todo: actually test building with dkP.
This commit undoes most of PokeCodec's PRs after the debate in chat. Some harmless or completely superseded PRs have been left alone, as there is not much benefit in attempting to undo them. Reverts #1104, #1108, #1115, #1118, #1119, #1124, #1126, #1127, #1132, #1136, #1137, #1139, #1140, #1144, #1148, #1149, #1150, #1153, #1155, #1177, #1179, #1180, #1181, #1182 and #1183.