convert Redcap2ReproSchema.js to redcap2reproschema.py

[yibeichan]

here i converted/translated RedCap2ReproSchema.js to a python file reproschema/redcap2reproschema.py

Changes include:

• fully converted python file redcap2reproschema.py with unnecessary functions (e.g., create context file for each activity)
• created a template .yaml file (templates/redcap2rs.yaml) for predefined metadata
• integrated the tool with CLI
• updated README.md with instructions on how to use it as CLI and as a python function

[yibeichan]

i tested it using a redcap dictionary (two assessments combined from the redcap library) and the outputs are here, pretty good

[yibeichan]

i realized that we don't need to specify a github handler in this case. in the javascript version, it (github repo url) was needed to generate protocol-specific context. we don't need such context here.
also, I added a test for testing redcap2reproschema in cli. it worked.

so, this PR is 100% done. I'm gonna move to other tasks.