Add unit test for get_analysis_info flow.cylc utility

[ceblanton]

Currently, get_analysis_info is a python utility that forms the climatology-related task graphs and task definitions, via Jinja2 templating:

    {{ config | get_analysis_info('task-graph', PP_COMPONENTS, config['directories']['postprocess'], config['postprocess']['settings']['pp_start'], config['postprocess']['settings']['pp_stop'], config['postprocess']['settings']['pp_chunks'], postprocess['switches']['do_analysis_only']) }}

   {{ config | get_analysis_info('task-graph', PP_COMPONENTS, config['directories']['postprocess'], config['postprocess']['settings']['pp_start'], config['postprocess']['settings']['pp_stop'], config['postprocess']['settings']['pp_chunks'], postprocess['switches']['do_analysis_only']) }}

    {{ config | get_analysis_info('task-definitions', PP_COMPONENTS, config['directories']['postprocess'], config['postprocess']['settings']['pp_start'], config['postprocess']['settings']['pp_stop'], config['postprocess']['settings']['pp_chunks'], False ) }}

While E2E functionality is tested elsewhere, functionality for this subtool needs to be ensured. This issue tracks the development of a pytest unit test to verify the creation of analysis task graphs and definitions.

Examples could be:

1. Every-chunk timeseries analysis
2. Defined-range timeseries analysis
3. Cumulative-chunk timeseries analysis