[quant][executorch] Support quant fusion for cat in quant in executorch stack (#88960)
Summary:
* added cat in executorch backend config
* added quant fusion for "dq - cat - q" pattern
Test Plan: buck run executorch/exir/tests:quant_fusion_pass -- "executorch.exir.tests.test_quant_fusion_pass.TestQuantFusionPass.test_cat"
Reviewed By: qihqi
Differential Revision: D41111054
Pull Request resolved: https://github.com/pytorch/pytorch/pull/88960
Approved by: https://github.com/JacobSzwejbka
