Add separate shift keys for new touch controls

When using the new touch controls on mobile, I am unable to sneak and place blocks on any level except the lowest level while in a scaffolding climb state, and cannot sneak and place blocks in the air while flying in creative mode, which causes me to open containers or interactive interface. On PC, you can place blocks in the above two situations by holding down the jump key and sneak key at the same time without interacting with interactive blocks (such as opening the interactive interface, opening the box). Hopefully adding a separate sneak button, (or mapping the move down button to sneak?) which would solve some of the inconveniences on mobile devices. The current down key only moves players downward, unlike the PC shift key.