feat: automatically detect input format for template construction and collection CLI

[alexander-held]

As raised in cabinetry/cabinetry-tutorials#20 and mentioned in #291: the cabinetry templates CLI so far has not supported histogram inputs. By checking for "Tree" properties of samples, which are mandatory for ntuple inputs, we can determine it the input most likely has ntuple format. This could theoretically fail if configs are written for histograms but still set these tree properties (which do nothing in that case), so a --input_type override can be used to correct the automatic detection if needed.

The logic for the input format detection may need to be updated in case of config format changes, e.g. for features discussed in #291, #435, or #528.

resolves cabinetry/cabinetry-tutorials#20

* support histogram input reading through the command line interface
* automatically detect if input files have ntuple or histogram type
* new --input_type override to `cabinetry templates` to manually set input type

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 100.00%. Comparing base (54985d0) to head (5cc4bbc).
⚠️ Report is 4 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff            @@
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  Coverage   100.00%   100.00%           
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  Files           22        22           
  Lines         2099      2106    +7     
  Branches       291       293    +2     
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+ Hits          2099      2106    +7     

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