[BYOC][ACL] Add support for dense (fully connected) layer (#6254)

[BYOC][ACL] Add support for dense (fully connected) layer (#6254)

* [BYOC][ACL] Add support for dense (fully connected) layer

This patch adds the ability to offload dense (or fully connected) operators to ACL.

For fp32 a single dense layer can be offloaded, or the composite variant: nn.dense, nn.bias_add? (ACL does not currently offer fused activation).
For uint8: qnn.dense, nn.bias_add?, qnn.requantize

Change-Id: I83ea00b2aa6bdc5d9ef5cd6d54bbf981e523bd14

* Don't offload dense layer with unsupported datatype

Change-Id: I856eb2298499fdf22c172ba7f85d21033d3cc920