(Java) Allow /effect, /title times, and /weather to use the new time unit syntax

In the 1.14 snapshots, we've gotten the ability to use time units in the commands /time and /schedule. We can write 15s for 15 seconds, 25t for 25 ticks, or 2.5d for two and a half in-game days. This syntax should be made available to every command that deals with time.

/effect — We'd finally be able to give potion effects that last less than a full second.

/title <target> times — We'd be able to give timings in units that are more intuitive than game ticks.

/weather — We'd be able to be more precise and start sub-second amounts of weather, but more importantly we could easily start (for example) a full day of rain, without having to calculate how many seconds that is.

We could also add it to /setidletimeout, but that's usually in minutes. Of course, we could also allow minutes (5m) for all commands.

I would also suggest adding it to /worldborder, but that command works based on real time instead of game time. It could potentially still use some or all of the units, but ticks or days might not line up with actual in-game ticks and days if the game was lagging.