C-API quantization core proposal

[sfraczek]

Hi,
Please review our proposal of the C-API quantization design. The functionality is not fully complete yet, this is the core part. We are still developing the passes.

[luotao1]

There are so many un-related changes in this PR. Could you put them in a sperate PR (maybe we
can merge it) and make this PR more cleaner at first? For example,

• add sfraczek to authors.md
• paddle/fluid/framework/ir/xxx_pass.h: const->const override
• fix typo releated->related
• paddle/fluid/inference/tests/api/analyzer_xxx_tester.cc: reinterpret_cast<const PaddlePredictor::Config *>(&config)->&config

[luotao1]

The functionality is not fully complete yet, this is the core part. We are still developing the passes.

Thanks for your work. It seems good in general for me. I will invite other reviewers after this PR become much cleaner.

[wojtuss]

This PR is updated and turned into final one: #15987