Tracker ticket for alibi-explain tickets

[seldondev]

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Here are a list of tickets that might affect alibi-explain runtime:

Allow to specify channel dimension in data:https://github.com/SeldonIO/alibi/issues/487

AnchorImage will fail with != fp64 models:https://github.com/SeldonIO/alibi/issues/499

AnchorImage image_shape as List (needed for on the fly init):https://github.com/SeldonIO/alibi/issues/493

Target in IntegratedGradients:https://github.com/SeldonIO/alibi/issues/492

Alibi factory of explainers:https://github.com/SeldonIO/alibi/issues/494

Validate explain parameters:https://github.com/SeldonIO/alibi/issues/488