Command autocomplete doesn't sort strings that start with the given word to the top

The bug

The command autocomplete feature in the 1.16 snapshots now also considers parts following an underscore when searching for possible completions. However, this causes an issue when quickly typing commands.

For instance, when typing /setblock ~ ~ ~ sandston, the first result is minecraft:chiseled_red_sandstone, which is most likely not the block that should be on top and automatically selected.

This causes annoying delays when typing commands since the user needs to type the word fully (thus making the autocomplete feature superfluous) or use the arrow keys to scroll to the correct (short) word (which takes some time).

Instead, strings that do not start with the given string but have the given string following an underscore should be sorted below the strings that start with the given string.

Examples

• /setblock ~ ~ ~ dir
  → minecraft:coarse_dirt
• /setblock ~ ~ ~ ston
  → minecraft:chiseled_stone_bricks
• /setblock ~ ~ ~ sandston
  → minecraft:chiseled_red_sandstone
• /setblock ~ ~ ~ terracott
  → minecraft:black_glazed_terracotta
• /summon minecar
  → minecraft:chest_minecart