[Do Not Merge] WIP - show payload data in task apis

[juribe80]

Issue number of the reported bug or feature request: RDISCROWD-8322

Describe your changes
A clear and concise description of the changes you have made.

Goal:

• In the tasks API, for projects that have private request fields we should replace the bcos file link with the actual private request field values by fetching the data from bcos
• Similarly, for the task run API, for projects that have private response fields we should replace the bcos file links with the actual private response field values by fetching the data from bcos

Testing performed
Describe the testing you have performed to ensure that the bug has been addressed, or that the new feature works as planned.

Additional context
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[coveralls]

Pull Request Test Coverage Report for Build 17588147346

Details

• 74 of 80 (92.5%) changed or added relevant lines in 3 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage decreased (-0.02%) to 94.039%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
pybossa/api/task.py	40	46	86.96%

Totals
Change from base Build 16990682200:	-0.02%
Covered Lines:	17859
Relevant Lines:	18991

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💛 - Coveralls