LMS-1467 Allow multiple users to edit the same schedule

Feature summary request

Allow multiple users to work on the same schedule, by fragmenting/locking schedules at lower levels (e.g. schedule paragraphs).

Currently, Lawmaker fragments a Bill at the level of sections and schedules and, as a result, those are the level at which locks operate too. This means that multiple users cannot edit the same schedule as the whole schedule might be locked by a single user. It is worth noting that schedules can be quite big in size - fragmenting schedules at lower levels would also allow users to edit portions of a schedule.

When looking at this feature improvement, attention should be paid to the performance consequences of fragmenting a schedule at lower levels, as this would massively increase the number of locks and thus have an impact on performance.

Original description

When working in a Schedule, a lock is always acquired for the whole Schedule. This prevents more than one user working on a Schedule at a time (and they can be quite big - sometimes bigger than Parts of Bills). Ideally locks would engage at the Schedule Paragraph level.

This is linked in a way to the request about yellow underlines on multiple schedules (as the user is getting around this by artificially having two Schedules which will be merged in due course - and is annoyed that the workaround is having that effect)..