Add --sync to global flags

[avoidik]

Hello from a curious person who sees Rye for the first time!

I was exploring a rye a bit and came to a conclusion that almost all operations with the cli are revolving around specific pattern, like:

• rye [cmd]
• rye sync

wouldn't make sense to introduce a global flag --sync so that we can optimize it just to one step, like:

• rye [cmd] --sync

meanwhile rye sync stays as is

what do you think?

[mitsuhiko]

My desire is to eventually make sync in most cases automatic. This will require a dramatically faster installation process though.