Add native exfat renaming support

[leigh123linux]

Fixes: #2708

[eyalroz]

So what exactly changes with this PR merged?

[leigh123linux]

@eyalroz It adds support for kernel exfat.
Microsoft files systems can't handle some characters, see

nemo/libnemo-private/nemo-file-operations.c

Line 3393 in def5cf2

#define FAT_FORBIDDEN_CHARACTERS "/:*?\"<>\\|"

[eyalroz]

@leigh123linux : I know, I filed #2708 ; I mean, in what sense is support added? What happens now when you copy to/from exfat and some characters are unsupported?

[mtwebster]

Any invalid characters are replaced with an underscore _.

[eyalroz]

@mtwebster : Ah, ok, now I get it.

What if there's a clash with another file? e.g. hello_world.txt and hello:world.txt?

[mtwebster]

It will prompt you to rename the second file. I'm not crazy about this - I'd prefer it add the normal (Copy) suffix to the name, but I imagine the actual frequency of this happening will be low. Plus the current behavior has been in place for many other file systems for a while.