W3C compliant actions protocol binding

[benfrancis]

This is an implementation to make the invoke action part of the gateway's API W3C compliant and is a partial fix to #2807.

• Remove object wrapper from invoke action API requests (to make action inputs directly match the action input data schema in Thing Descriptions)
• Update the front end to consume the new API
• Fix integration tests

My current thinking is to leave the rest of the API intact until the proposed action protocol binding for WoT Profile is finalised, so that we don't have to implement it twice. The first step is to simply make the invokeaction operation API match the Thing Description.

One thing I'm not sure about is what to do with the /actions endpoint where no action name is specified in the URL, but one option is to leave it as it is and just remove that endpoint from Thing Descriptions until the Thing Description specification has a way to describe it (see w3c/wot-thing-description#1200).

[codecov-commenter]

Codecov Report

Merging #2871 (e79ce4a) into master (7a4c641) will increase coverage by 0.09%.
The diff coverage is 42.85%.

❗ Current head e79ce4a differs from pull request most recent head 7bcd592. Consider uploading reports for the commit 7bcd592 to get more accurate results

@@            Coverage Diff             @@
##           master    #2871      +/-   ##
==========================================
+ Coverage   65.30%   65.40%   +0.09%     
==========================================
  Files         124      124              
  Lines        7987     7974      -13     
  Branches     1320     1317       -3     
==========================================
- Hits         5216     5215       -1     
+ Misses       2729     2717      -12     
  Partials       42       42              

Impacted Files	Coverage Δ
src/models/thing.ts	68.93% <0.00%> (+0.11%)	⬆️
src/controllers/actions_controller.ts	89.36% <40.00%> (+4.17%)	⬆️
src/app.ts	56.32% <100.00%> (ø)
src/plugin/plugin.ts	60.66% <0.00%> (+0.47%)	⬆️
src/controllers/groups_controller.ts	27.73% <0.00%> (+0.72%)	⬆️
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]

I've fixed the integration tests and this is now ready for review.

What this PR does:

• Removes the object wrapper from invokeaction operations on Action endpoints (e.g. /things/mything/actions/foo) so that the payload directly matches the input schema for the action affordance in the Thing Description

What this PR does not do:

• Change the API for querying or cancelling an action
• Change the API for invoking an action via an Actions endpoint (e.g. /things/mything/actions/)

My thinking is that in this first phase we will just make the invokeaction and queryallactions operations W3C compliant in order to be able to provide a W3C compliant Thing Description. The API for the other operations will still exist, it just won't be described by the Thing Description.

In a later phase we can fully implement the new actions protocol binding from the WoT Profile specification and also expose queryaction and cancelaction operations in Thing Descriptions.

Note that we will need to add the new queryallactions operation to Forms in #2811.

[benfrancis]

@relu91 FYI I think we need to land this before landing relu91#2 and #2811 because they are starting to conflict with one another.

[relu91]

No objections! looks good.