[Enhancement] Support noise offset in stable diffusion training

[LeoXing1996]

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Motivation

Support noise offset introduced by https://www.crosslabs.org/blog/diffusion-with-offset-noise, which enables stable diffusion to generate lighter or darker images.

Modification

As title.

BC-breaking (Optional)

Does the modification introduce changes that break the backward-compatibility of the downstream repositories?
If so, please describe how it breaks the compatibility and how the downstream projects should modify their code to keep compatibility with this PR.

Use cases (Optional)

If this PR introduces a new feature, it is better to list some use cases here, and update the documentation.

Checklist

Before PR:

• I have read and followed the workflow indicated in the CONTRIBUTING.md to create this PR.
• Pre-commit or linting tools indicated in CONTRIBUTING.md are used to fix the potential lint issues.
• Bug fixes are covered by unit tests, the case that causes the bug should be added in the unit tests.
• New functionalities are covered by complete unit tests. If not, please add more unit test to ensure the correctness.
• The documentation has been modified accordingly, including docstring or example tutorials.

After PR:

• If the modification has potential influence on downstream or other related projects, this PR should be tested with some of those projects.
• CLA has been signed and all committers have signed the CLA in this PR.

[codecov]

Codecov Report

Patch coverage: 50.00% and project coverage change: -0.01 ⚠️

Comparison is base (5f62dee) 83.00% compared to head (aa551a8) 83.00%.

❗ Current head aa551a8 differs from pull request most recent head bd370ca. Consider uploading reports for the commit bd370ca to get more accurate results

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1880      +/-   ##
==========================================
- Coverage   83.00%   83.00%   -0.01%     
==========================================
  Files         411      411              
  Lines       27603    27607       +4     
  Branches     4316     4317       +1     
==========================================
+ Hits        22913    22915       +2     
- Misses       3754     3756       +2     
  Partials      936      936              

Flag	Coverage Δ
unittests	83.00% <50.00%> (-0.01%)	⬇️

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Impacted Files	Coverage Δ
mmagic/models/editors/controlnet/controlnet.py	50.17% <ø> (ø)
mmagic/models/editors/dreambooth/dreambooth.py	63.75% <ø> (ø)
...odels/editors/stable_diffusion/stable_diffusion.py	59.16% <50.00%> (-0.16%)	⬇️

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