Add conversion for count/min samples (e.g. HeartRate)

[camposer]

Description

Unit conversion to double fails when consuming count/min samples (e.g. HeartRate) in background mode. See here

Type of change

Please delete options that are not relevant.

• [X] Bug fix (non-breaking change which fixes an issue)
• [ ] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to not work as expected)
• [ ] This change requires a documentation update

Checklist:

• [X] My code follows the style guidelines of this project
• [X] I have performed a self-review of my own code
• [ ] I have made corresponding changes to the documentation
• [X] I have checked my code and corrected any misspellings