Create separate sample_data_type records for different sections

[djwooten]

PR Checklist

• [x] This comment contains a description of changes (with reason)
• [x] Referenced issue is linked
• [ ] If you've fixed a bug or added code that should be tested, add tests!
• [ ] Documentation in docs is updated
• [ ] docs/changelog.md is updated

Description of changes

• Fixes https://github.com/MultiQC/MegaQC/issues/530
  • When handling a report, megaqc checks to see if that SampleDataType already exists. However it only checks on the basis of data_id, but ignores data_section. Therefore if multiple report types (data sections) reuse the same data_id, currently this will reuse that SampleDataType even if data_section is wrong for the incoming report.
• This PR adjusts the logic so that it checks for previous SampleDataType entries based on data_key, which includes both data_id and data_section.