rust: crate_tool: Sort patches directory before using

Patches sometimes intentionally have `0001`, `0002`, etc. or other
alphabetization methods to indicate what order patches should be applied
in. Previously, we gathered up patches in directory-walk order, which
sometimes resulted in patches not applying.

Bug: 388276112
Test: ./crate_tool regenerate rustc-demangle-capi
Change-Id: Ic66b10024908a86dcf3ec13d0fb901333696966f