Feat/timeline schema changes

Sub-branch from #260

Implements new function to calculate timeline
getTimeline function is agnostic of CosmosEvent or CosmosMessage input to replace logic for all entities, apart from transaction
Modifies timeline calculation with correct constants & logic

Code Review Checklist (to be filled out by reviewer)

[ ] Description accurately reflects what changes are being made.
[ ] Either the PR references an issue (via the "Development" combobox) or the description explains the need for the changes.
[ ] The PR appropriately sized.
[ ] The PR contains an idempotent DB migration.
[ ] I have verified the correctness of the DB migration using relevant data (e.g. test-generated data).
[ ] New code has enough tests.
[ ] New code has enough documentation to answer "how do I use it?" and "what does it do?".
[ ] Existing documentation is up-to-date, if impacted.