[$] Kernel time APIs for Rust

While the 6.3 kernel has gained more support for the Rust language, itstill remains true that there is little that can be done in Rust beyond thecreation of a "hello world" module. That functionality was alreadyavailable in C, of course, with a level of safety similar to what Rust canprovide. Interest is growing, though, in merging actually useful moduleswritten in Rust; that will require some more capable infrastructure than iscurrently present. A recent discussion on the handling of time values inRust demonstrates the challenges - and opportunities - inherent in thiseffort.