Other related changes:

- core_analytics\site get_start and get_end returning always integer values
- Defer intval call in define_ranges to refine some seconds

Revert the change I made in MDL-59382 to correctly set the id for inline
form elements because it's breaking a bunch of different places that had
already worked around the problem.

It's impossible to gain the right colour contrast against a dark footer
using the same primary colour that gets 4.5 against white.

For historical reasons repositories need to call add_file_to_pool
to sync file records. However now that a before_file_created hook
has been added additional information is needed by add_file_to_pool.

Ideally add_file_to_pool and friends will become private/protected,
so we need to remove all uses of it in core.

This patch adds some new methods to the file class to allow syncing
to be managed internally by the file and the file_storage class.