[ENH] Add AEBiGRUNetwork

[aadya940]

Implements Auto-Encoder based on BiDirectional GRU Network.

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[hadifawaz1999]

this is good to go, just need the test to assert the shapes of input and output of the network are the same

[hadifawaz1999]

lgtm

[aadya940]

this is good to go, just need the test to assert the shapes of input and output of the network are the same

Already done in test_all_networks.py.

[aadya940]

There's a mistake here.
_config.structure should be "auto-encoder" not "encoder".