[qunat][graphmode][fx] Embedding/EmbeddingBag works in static quant qconfig (#48062)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/48062
When Embedding/EmbeddingBag are configured with static quant we'll skip inserting observer for
them in the graph and keep the op unchanged and print a warning.
This also aligns with eager mode behavior as well.
We'll enforce this behavior for other ops that only supports dynamic/weight_only quant but not static quant as well.
We used a global variable `DEFAULT_NOT_OBSERVED_QUANTIZE_HANDLER`, this is not exposed to user right now,
we can add that later if needed.
Test Plan: Imported from OSS
Reviewed By: supriyar
Differential Revision: D25007537
fbshipit-source-id: 6ab9e025269b44bbfd0d6dd5bb9f95fe3ca9dead
