Add filesystem UUID based filter

[erjavaskivuori]

Add filesystem UUID based filter to the filesystemCollector

The implementation currently only includes Linux and I would be glad to hear feedback before continuing to implement this for other OS' file system collectors.

I tried to create unit test for the buildUUIDMap function but couldn't figure out how could I create device major:minor for the fixture block device nodes that I tried to add. So currently there is no test for this feature. I have tested this locally.

Fixes #3380

[kashifest]

@SuperQ can we have reviews on this one?

[Rozzii]

@SuperQ I have took over this PR and I have also re-based it. Would it be possible to get some review on this PR?
I still think this PR could be beneficial for the wider community.

[Rozzii]

Adding @discordianfish too, please take a look.

[discordianfish]

Not completely opposed but also not convinced this is needed. You could use a wrapper script to lookup the mountpoints from the uuids and then invoke the node-exporter with the right mountpoint.
My main concern is that this is a slippery slope leading to more and more ways to ignore devices. Like why don't we support ignoring by device name? By serial numbers? etc..

@SuperQ wdyt?

[discordianfish]

Ah hah, see #3400
I'd say if we want to support this, we should come up with what to filter by (uuid, device etc) and figure out a consistent way to do that