(maint) explicitly require operating system fact dependencies

Commit 330166b954f9d1939af22adf5f24e4a59c706f65 introduced a dependency
on facter/util/file_read in the operatingsystem fact resolutions, but
did not explicitly require the class. This introduced a race condition
where loading facts in certain orders could cause an unitialized
constant error. This commit adds the needed require to ensure this works
correctly.
Merge branch 'maint-fedora_fileread'