[Waste] Factor out garden costs to single package.

[dracos]

Moves all garden costs/discount stuff to its own package which can then be queried for costs.
And adds a 'different price for first bin'
[skip changelog]

[codecov]

Codecov Report

Attention: Patch coverage is 94.01198% with 10 lines in your changes missing coverage. Please review.

Project coverage is 82.47%. Comparing base (fbbb05a) to head (3698b3d).

Files with missing lines	Patch %	Lines
perllib/WasteWorks/Costs.pm	93.96%	3 Missing and 4 partials ⚠️
perllib/FixMyStreet/Cobrand/Sutton.pm	60.00%	0 Missing and 2 partials ⚠️
perllib/FixMyStreet/Cobrand/Kingston.pm	80.00%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@                       Coverage Diff                       @@
##           bexley-ww-pre-work-refactor    #5324      +/-   ##
===============================================================
+ Coverage                        82.43%   82.47%   +0.03%     
===============================================================
  Files                              416      417       +1     
  Lines                            32904    32939      +35     
  Branches                          5278     5282       +4     
===============================================================
+ Hits                             27125    27166      +41     
+ Misses                            4221     4217       -4     
+ Partials                          1558     1556       -2     

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[MorayMySoc]

I've left a couple of incidental comments that are just very minor queries of style, but this seems to work according to the tests. As you say, direct tests on the new package would help confirm its reliability.

[dracos]

Moved service inside Costs.pm; then made some small additional changes - moved _get_costs into the Costs.pm as well, small wording changes, put all the cobrand bits together. Then noticed end date could be taken from the service as well mostly, so moved that out of some calls. And added a tests file. Probably worth a re-review, check my tests look as you'd expect :)

[MorayMySoc]

Ok, this looks good to me.