The fs_query component queries and monitors information stored on a file
system. The file system is configured as a component-local VFS. The component
accepts any number of 'query' nodes within its 'config' node. Each
'query' node must contain a 'path' attribute pointing to a directory to
watch. The component generates a report labeled "listing". For each
existing queried directory, the report contains a 'dir' node with the
list of files as 'file' nodes featuring the corresponding 'name' as
attribute value.

A 'query' can be equipped with a 'content' attribute. If set to 'yes', the
content of the queried files is supplemented as body of the 'file' nodes. The
reported content is limited to 4 KiB per file. If the content is known to be
valid XML, the 'file' node can be equipped with the attribute 'xml' set to
'yes' indicating that the file content can be inserted as is. Otherwise, the
content is sanitized.

If the query attribute 'count' is set to 'yes', the reported 'dir' nodes
deliver an overview of the directory content as attributes 'num_dirs',
'num_files', and 'num_symlinks'.

Furthermore, a query can contain a 'size' attribute. If set to 'yes', the size
of each queried file in bytes is reported as 'size' attribute in the
corresponding 'file' node.
