[MC-237301] /loot tool argument is ambiguous

In the /loot command the <tool> argument (for the mine/fish options) is ambiguous with mainhand and offhand input.

/effect was split up to /effect give and /effect clear for exactly this reason.

Current synaxt:

/loot <...> mine <x> <y> <z> <tool>|mainhand|offhand
/loot <...> fish <loot table> <x> <y> <z> <tool>|mainhand|offhand

Expected synaxt:

/loot <...> mine <x> <y> <z> mainhand|offhand
/loot <...> mine <x> <y> <z> tool <tool>
/loot <...> fish <loot table> <x> <y> <z> mainhand|offhand
/loot <...> fish <loot table> <x> <y> <z> tool <tool>