Expose reclocking information as a relation in Materialize

[petrosagg]

The storage controller currently exposes collections identified by a GlobalId. These collections correspond 1-1 to a TVC that one can read by demonstrating its id.

We would like to change this relationship so that each storage collection correspond to two parts (maybe more in the future), its data and its timestamp binding TVCs. Users of storage will now need to specify which part of a storage collection they need by specifying an (id, type) tuple.

Implementing this depends storing the timestamp bindings in a persist collection (#11907) so that readers can read the data.

[benesch]

And there's a design nearing completion in #11718!

[sploiselle]

I have a nitty-gritty design doc for this in Notion.

[sploiselle]

Note that before we do this we want to migrate this data to the more Timely-friendly format which Petros is already doing in memory

[aljoscha]

Implemented as #15813