Rework API to reflect desired user interface

[tpoliaw]

Reduce the query space to searching by instrument session for runs and
within runs for data.

Stops the API being as tightly coupled to the internal structure of
tiled.

[codecov]

Codecov Report

❌ Patch coverage is 2.82486% with 172 lines in your changes missing coverage. Please review.
✅ Project coverage is 37.02%. Comparing base (01f835d) to head (813dd6a).
⚠️ Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
src/model.rs	0.00%	64 Missing ⚠️
src/download.rs	0.00%	58 Missing ⚠️
src/clients.rs	7.31%	38 Missing ⚠️
src/main.rs	0.00%	7 Missing ⚠️
src/model/container.rs	0.00%	5 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##             main      #75       +/-   ##
===========================================
- Coverage   74.70%   37.02%   -37.69%     
===========================================
  Files          12       12               
  Lines         514      443       -71     
===========================================
- Hits          384      164      -220     
- Misses        130      279      +149     

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[abbiemery]

As discussed, this is the first pass of getting an interface that delivers us what we want. To avoid holding things up I think we get this in. Remove the test todo and write tests in a following pr. If time permits before friday grand. If not, we can do them once we reorganise this somewhat.