Glob search order should be "specified"

Currently, [Package Searching](https://cps-org.github.io/cps/searching.html) gives a list of paths and specifies the order in which each item should be searched. However, some *items* involve globs. We should document the order in which matching globs are searched, even if that order is "unspecified" or "implementation defined".

Note that CMake appears to use [`CMAKE_FIND_PACKAGE_SORT_ORDER`](https://cmake.org/cmake/help/latest/variable/CMAKE_FIND_PACKAGE_SORT_ORDER.html) and [`CMAKE_FIND_PACKAGE_SORT_DIRECTION`](https://cmake.org/cmake/help/latest/variable/CMAKE_FIND_PACKAGE_SORT_DIRECTION.html) to control this order; it would be helpful for CMake's implementation if whatever we specify is compatible with this.