Add templates for data tables

[brynpickering]

Fixes #676

Reviewer checklist

• Test(s) added to cover contribution
• Documentation updated
• Changelog updated
• Coverage maintained or improved

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 95.97%. Comparing base (a9a610e) to head (bf68920).
Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff            @@
##             main     #695    +/-   ##
========================================
  Coverage   95.96%   95.97%            
========================================
  Files          29       29            
  Lines        4039     4048     +9     
  Branches      848      578   -270     
========================================
+ Hits         3876     3885     +9     
  Misses         72       72            
  Partials       91       91            

Files with missing lines	Coverage Δ
src/calliope/model.py	96.00% <100.00%> (+0.07%)	⬆️
src/calliope/preprocess/data_tables.py	100.00% <100.00%> (ø)
src/calliope/preprocess/model_data.py	100.00% <100.00%> (ø)
src/calliope/util/tools.py	94.59% <100.00%> (+4.59%)	⬆️

... and 2 files with indirect coverage changes

[sjpfenninger]

A great idea. Just some comments on making climb_template_tree() easier to understand.

[brynpickering]

Hopefully fixes all work for you @sjpfenninger !