[WIP] Initial multisession and session resume support

[a-hurst]

PR Description

This PR adds basic multi-session project support to klibs. It supports reloading existing participants for additional sessions, checking the progress of participants across multiple sessions, and resuming/restarting/skipping incomplete sessions.

TODO:

• Separate unique ID collection from other demographics queries
• Update data export to properly check the 'complete' status of multi-session projects
• Add support for reloading existing participants for multi-session projects
• Add support for resuming incomplete sessions
• Add support for redoing incomplete sessions
• Add support for skipping incomplete sessions
• Add block_num and trial_num to required columns for primary table?
• Add support to klibs create for easily creating multi-session projects
• Clean up 'versions' folder handling in collect_demographics?
• Break collect_demographics into sub-functions?

Additionally, this PR improves how KLibs handles demographics collection:

• If a user query does not have a corresponding database column (or the column allows null values), it will be skipped. This means you only have to remove a query in one place (the database) to toggle it off instead of in the user_queries file as well.
• If an experiment reaches the start of the first block without demographics being collected, it will raise an exception.

Merge Checklist

• the PR has been reviewed and all comments are resolved
• all CI checks pass
• (if applicable): the PR description includes the phrase closes #<issue-number> to automatically close an issue
• (if applicable): bug fixes, new features, or API changes are documented in CHANGELOG.rst