oxenstored: move functions that process simple operations

oxenstored: move functions that process simple operations

Separate the functions which process operations that can be done as part of a
transaction. Specifically, these operations are: read, write, rm, getperms,
setperms, getdomainpath, directory, mkdir.

Also split function_of_type into two functions: one for processing the simple
operations and one for processing the rest.

This will help allow replay of transactions, allowing us to invoke the functions
that process the simple operations as part of the processing of transaction_end.

Signed-off-by: Jonathan Davies <jonathan.davies@citrix.com>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jon Ludlam <jonathan.ludlam@citrix.com>
Reviewed-by: Euan Harris <euan.harris@citrix.com>
Acked-by: David Scott <dave@recoil.org>