Add community pipeline for semantic guidance for FLUX

[Marlon154]

What does this PR do?

This PR adds the new FluxSemanticGuidancePipeline to enable semantic guidance (original paper) capabilities in the Flux model family. Works like already existing semantic guidance pipelines.
Example on usage is in the doc string, it works with:

• FLUX adapters
• Multiple images per prompt
• Multiple prompts
• CFG with negative prompt
• Without CFG

Examples

Prompt	Original	Edit	Edited
A cat holding a sign that says hello world		remove "cat", add "dog"
race car on a track		add "black sports car"
A sports car under a tree. (with adapter)		add "apple tree", add "dog sitting on the right side of a car"

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Who can review?

@linoytsaban

[linoytsaban]

great work, thanks @Marlon154!

[hlky]

Thanks!

[Marlon154]

@hlky implemented requested changes