[odu] Simplify Support operations

Supported operations will be used during argument parsing
to varify that Target supports requested operations. For example
if user wants to stress file creation then to verify we need
Target to support readdir and opendir.

There is no need to have current Option<> in TargetOps structure.

Test: fx run-test odu_tests

Change-Id: Ic5821433f67ca2cdc32d6b7076d4fe278047bfc0