Add functionality to pull data from multiple containers per phone sensor

[jenniferfedor]

For many of our studies, data for some phone sensors that are collected with high frequency like accelerometer are distributed across multiple database tables due to their size, and it's impractical to attempt to combine these data into a single container (database table, CSV file, etc.) prior to processing as we currently require.

This PR adds functionality to (1) allow the user to specify either a single item (e.g. accelerometer) or an array of items (e.g., [accelerometer, accelerometer_old]) for the data stream CONTAINER parameter for all phone sensors and (2) loop through any specified data stream containers for that sensor in the pull_phone_data.R script. We assume as always that all data for a given sensor are formatted according to the respective mandatory phone format.