Description of problem:

Currently, mounting a filesystem by the device's label fails if there's a space between "-L" and the label. For example, `device="-L IPXE"`. This is because we double-quote the DEVICE variable, which prevents word splitting, when we use it in the mount command.

We can't remove the double quoting, because it was the fix for BZ 1624591, which enabled us to mount devices that **actually** have whitespace in their names.

So I think we have two options:

1. Add a flag (e.g., `uselabel=true`, with default value set to false) that tells the Filesystem resource agent to treat the `device` option as a device label instead of a device name. Then use `$MOUNT -L "$DEVICE"` instead of `$MOUNT "$DEVICE"` if uselabel=true. I favor this option.
2. Do nothing and simply instruct users to omit the space after the -L. So in our example, it would be `device="-LIPXE"` instead of `device="-L IPXE"`. I think this will work but it's a bit counterintuitive and harder to read.

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Version-Release number of selected component (if applicable):

resource-agents-4.1.1-98.el8

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How reproducible:

Always

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Steps to Reproduce:
1. Configure a Filesystem resource with a label in the device attribute (e.g., `device="-L mylabel"`).
2. Try to start the resource.

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Actual results:

ERROR: Couldn't mount device [-L mylabel] as /mnt/my_fs'

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Expected results:

Resource starts and filesystem mounts.