[Merton] Add button to reset discount

[dracos]

And a v basic Echo debug panel, mostly as an easy way to find the UPRN.

[skip changelog]

[codecov]

Codecov Report

❌ Patch coverage is 75.00000% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 83.41%. Comparing base (5b67ecf) to head (2e42091).

Files with missing lines	Patch %	Lines
perllib/FixMyStreet/App/Controller/Waste/Bulky.pm	71.42%	0 Missing and 2 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #6130      +/-   ##
==========================================
- Coverage   83.41%   83.41%   -0.01%     
==========================================
  Files         506      506              
  Lines       37897    37904       +7     
  Branches     6281     6283       +2     
==========================================
+ Hits        31613    31618       +5     
  Misses       4462     4462              
- Partials     1822     1824       +2     

☔ View full report in Codecov by Harness.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.