The source_hash parameter for file.managed doesn't support files of arbitrary (utf16) encoding

So, Lol. I wouldn't have thought this as being too common for it to be too big of a deal, but it turns out that the hash file for y'alls windows installer (https://repo.saltstack.com/windows/Salt-Minion-2018.3.3-Py2-x86-Setup.exe.md5) is a utf16 encoded md5. Due to it being utf16, the file.managed fails.

Here's a statefile:

Download Salt-Minion installer for windows:
    file.managed:
        - source: https://repo.saltstack.com/windows/Salt-Minion-2018.3.3-Py2-x86-Setup.exe
        - name: /path/to/wherever
        - source_hash: https://repo.saltstack.com/windows/Salt-Minion-2018.3.3-Py2-x86-Setup.exe.md5
        - mode: 0664

This results in:

vmware-iso: ----------
vmware-iso:           ID: Download Salt-Minion installer for windows
vmware-iso:     Function: file.managed
vmware-iso:         Name: /path/to/wherever
vmware-iso:       Result: False
vmware-iso:      Comment: Unable to manage file: 'ascii' codec can't decode byte 0xff in position 0: ordinal not in range(128)
vmware-iso:      Started: 10:52:51.086256
vmware-iso:     Duration: 326.789 ms
vmware-iso:      Changes:
vmware-iso:

This is in the 2019.2 branch. If you look in salt.modules.file, you can see that get_managed() will call salt.utils.hashutils.get_hash() in order to process the source_hash file. The salt.utils.hashutils.get_hash() function, which doesn't take any wildarg or kwarg parameters, then calls salt.utils.files.fopen() to open the file. Although salt.utils.files.fopen() function can take an encoding= parameter, the get_hash() function doesn't even bother since it only has three positional parameters and none of them are an encoding.

Start in salt.modules.file.get_managed() and follow its call to salt.utils.hashutils.get_hash(); then inspect how salt.utils.files.fopen() handles encoding. Done means file.managed can process a UTF-16 source_hash file without the reported decode error, with the relevant behavior covered by tests if the repository has them.