feat(LEDC): Add Gamma Fade support and enhance auto channel/timer selection for multi-group (#11464)

* feat(ledc): Enhance LEDC auto channel/timer selection for multi-group support

* feat(ledc): Add Gamma Fade support

* fix(example): Update comments

* ci(pre-commit): Apply automatic fixes

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Co-authored-by: pre-commit-ci-lite[bot] <117423508+pre-commit-ci-lite[bot]@users.noreply.github.com>

Author: P-R-O-C-H-Y