Support custom filesystem implementations

[brandonvin]

Can Trino support custom filesystems, possibly installed as plugins? In the Hadoop ecosystem, developers can add FileSystems fairly easily and there are situations where this has been quite useful for us.

[wendigo]

@brandonvin do you have specific filesystem type in mind or is this hipothetical ask? Since filesystems are used as a library, not as a plugin, this would complicate filesystem implementation and we don't want that