Support pickling the whole AutoML instance, Sync Fabric till 0d4ab16f

[thinkall]

Why are these changes needed?

• Previously, pickle the AutoML instance only works for non-spark models, with this PR, we add pickle and load_pickle methods for pickling the whole AutoML instance for both non-spark and spark models.
• Sync Fabric till 0d4ab16f

Related issue number

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• I've added tests (if relevant) corresponding to the changes introduced in this PR.
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