allow tasks environment variables to be set

[chkeita]

Summary of the Pull Request

introduce a new target_env parameter to specify the environment variable of a task

closes #1623

[codecov-commenter]

Codecov Report

Merging #3294 (735b8e9) into main (7a92dab) will increase coverage by 2.21%. The diff coverage is 18.18%.

@@            Coverage Diff             @@
##             main    #3294      +/-   ##
==========================================
+ Coverage   29.24%   31.46%   +2.21%     
==========================================
  Files         301      307       +6     
  Lines       35762    37202    +1440     
==========================================
+ Hits        10459    11704    +1245     
- Misses      25303    25498     +195     

Impacted Files	Coverage Δ
src/ApiService/ApiService/onefuzzlib/Defs.cs	0.00% <0.00%> (ø)
src/ApiService/ApiService/onefuzzlib/Scheduler.cs	14.43% <0.00%> (-0.08%)	:arrow_down:
src/agent/onefuzz-agent/src/debug.rs	0.00% <0.00%> (ø)
src/agent/onefuzz-agent/src/work.rs	17.91% <ø> (ø)
src/agent/onefuzz-agent/src/worker.rs	47.46% <0.00%> (-0.35%)	:arrow_down:
...c/agent/onefuzz-task/src/local/generic_analysis.rs	0.00% <0.00%> (ø)
...c/agent/onefuzz-task/src/tasks/analysis/generic.rs	0.00% <0.00%> (ø)
src/ApiService/ApiService/OneFuzzTypes/Model.cs	72.67% <50.00%> (-0.06%)	:arrow_down:
...e/onefuzzlib/notifications/JinjaTemplateAdapter.cs	90.75% <100.00%> (+0.02%)	:arrow_up:
src/agent/onefuzz-agent/src/agent/tests.rs	100.00% <100.00%> (ø)
... and 1 more

... and 36 files with indirect coverage changes