[uv] Use new uv.lock format in uv translator

[ddeville]

uv renamed distribution to package before stabilizing the lock file format.

Change this so that rules_pycross can use uv lock files generated with a recent version of uv.

[ddeville]

Ah oops just saw that there's an existing opened PR here.

[betaboon]

~@jvolkman could we get this merged in favor of #119 ?~

~i think the backwards-compatibility in #119 is not really required, and this pr covers the change with tests.~

just noticed: the changes in here seem insufficient. support for virtual contained in #119 is also required.

[betaboon]

resolved by #130