Add filter to exclude convert scores (Mania, Taiko, Catch)

Add a !c modifier to some commands to exclude scores on convert maps (maps that are from osu!standard and converted to the specified gamemode)

You can get countless #1 on convert leaderboards because nobody plays them, so it would be way better to compare some of the data, like the ones involving leaderboards, without converts (this applies to the three gamemodes)

It could be added to the following commands:
osustatsglobals, osustatscount, osustatslist, mapper and topif

Start by locating the implementations of osustatsglobals, osustatscount, osustatslist, mapper, and topif, then inspect how their leaderboard-related data is gathered for Mania, Taiko, and Catch. Confirm how convert maps are represented before deciding where the !c modifier belongs. Done means each listed command accepts !c and excludes converted scores from the relevant comparisons.