Age-region sampling enabled and other modifies

[YunliQi]

This pull request include:

1. Module to pre-process the data
2. Module to sample according to age and region distributions
3. Original idea to deal with the non-responders
4. Include the Github Actions
5. Test of pre-process module
6. Part of test of age-region sampling

Things incomplete:

• Test of non-responder module
• Test of age-region sampling
• Documentation of all tests

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