This PR adds support for passing the NDArrays from the existing optimize_for API down to the reviewSubgraph function in an external library. It also adds a new API for HybridBlock called optimize_for that can partition the model without running a forward pass.

Feature changes

    Adds new API to HybridBlock optimize_for that partitions the model but does not call the cachedOp
    Modifies the subgraph library example to optionally require args to be provided
    Adds annotation on subgraph inputs for the name of the original param so that inputs can be mapped and passes annotations to input nodes of subgraphs
    Adds support for tensors in MKLDNN format, calls Reorder2Default

New tests

    Adds a new test to partition operators that directly consume params
    add a new model to test where ops to be partitioned have args/params

Bug Fixes

    fixes bug in passing ids vector by value instead of by reference
    fixes bug in passing copies of attributes instead of by reference
    fixes bug where _cached_graph was not updated after partitioning
    fixes memory leak where user-specified attributes on subgraph ops were not freed if subgraph was rejected
    fixes problem incorrectly indexing into shape/dtype maps when annotating the graph

Docs

    Updates the README doc with the latest changes described above