client and API: add plan class to APP_INIT_DATA

[davidpanderson]

This is needed for the Docker wrapper;
image names must be unique for app versions, so they must include project URL, app name, plan class, and version.

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 28 lines in your changes missing coverage. Please review.

Project coverage is 10.51%. Comparing base (711d4f1) to head (d18d4c5).
Report is 2 commits behind head on master.

Files with missing lines	Patch %	Lines
lib/app_ipc.cpp	0.00%	25 Missing ⚠️
lib/proxy_info.h	0.00%	3 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##             master    #5830      +/-   ##
============================================
- Coverage     10.51%   10.51%   -0.01%     
  Complexity     1068     1068              
============================================
  Files           280      280              
  Lines         36019    36021       +2     
  Branches       8444     8441       -3     
============================================
  Hits           3789     3789              
- Misses        31841    31843       +2     
  Partials        389      389              

Files with missing lines	Coverage Δ
lib/app_ipc.h	0.00% <ø> (ø)
lib/proxy_info.h	0.00% <0.00%> (ø)
lib/app_ipc.cpp	0.00% <0.00%> (ø)