W3C compliant properties protocol binding

[benfrancis]

This is a replacement for #2868 which makes the properties part of the gateway's API W3C compliant and is a partial fix to #2807. Unlike #2868, set property operations still have a payload in their response since it turns out the front end depends on this.

• Remove object wrapper from property API requests (to make API payloads directly match property data schema in Thing Descriptions)
• Update the front end to consume the new API
• Fix the litany of failing integration tests as a result of changing the API

[codecov-commenter]

Codecov Report

Merging #2875 (0a65023) into master (7a4c641) will decrease coverage by 0.00%.
The diff coverage is 90.00%.

❗ Current head 0a65023 differs from pull request most recent head 5f0b6ba. Consider uploading reports for the commit 5f0b6ba to get more accurate results

@@            Coverage Diff             @@
##           master    #2875      +/-   ##
==========================================
- Coverage   65.30%   65.30%   -0.01%     
==========================================
  Files         124      124              
  Lines        7987     7984       -3     
  Branches     1320     1320              
==========================================
- Hits         5216     5214       -2     
+ Misses       2729     2728       -1     
  Partials       42       42              

Impacted Files	Coverage Δ
src/controllers/things_controller.ts	79.48% <85.71%> (-0.84%)	⬇️
src/app.ts	56.32% <100.00%> (ø)
src/test/browser/test-utils.ts	95.12% <100.00%> (ø)
src/controllers/internal_logs_controller.ts	84.21% <0.00%> (-1.76%)	⬇️
src/models/thing.ts	69.20% <0.00%> (+0.38%)	⬆️
src/models/things.ts	76.68% <0.00%> (+1.22%)	⬆️
src/controllers/new_things_controller.ts	46.15% <0.00%> (+2.56%)	⬆️

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[benfrancis]

OK, I finally got all the tests to pass which was a bit of a mission. Ready for review.