Rename UTIL_getFileStat() -> UTIL_statFile() and UTIL_getDirectoryStat() -> UTIL_stat...

Rename UTIL_getFileStat() -> UTIL_statFile() and UTIL_getDirectoryStat() -> UTIL_statDir()

I want to introduce versions of many of these functions that take pre-
populated `stat_t` objects and use those rather than doing their own redundant
`stat()` internally. These functions will have `...Stat()` suffixes. So this
commit renames these existing functions into the active voice, to avoid
confusion.