✨ add multiple phenotypes to samples

[bunop]

Description

This PR will add multiple phenotypes to samples by adding a new import_multiple_phenotypes.py script

Related Issue

closes #103

Motivation and Context

This PR is required to add multiple phenotypes to the same samples

How Has This Been Tested?

Changes were tested with CI, by loading multiple phenotypes and then ensuring SMARTER-backend, r-smarter-api and SMARTER-frontend work without problems

Screenshots (if appropriate):

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Refactoring (non-breaking change which improve code itself)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• All new and existing tests passed.

[coveralls]

coverage: 94.293% (-0.1%) from 94.419% when pulling 4ac42ad on issue-103 into ceabf8c on devel.