feat(api): Add a log aggregation optout

[sfoster1]

We already have the /settings/log_level/upstream, but it's a lot easier to add a
simple advanced setting that disables the aggregation, which the app can trigger
a modal on.

Also refactors syslog control out of the endpoint implementation.

Closes #3866

[codecov]

Codecov Report

Merging #3868 into edge will decrease coverage by 0.13%.
The diff coverage is n/a.

@@            Coverage Diff            @@
##             edge   #3868      +/-   ##
=========================================
- Coverage   34.43%   34.3%   -0.14%     
=========================================
  Files         743     743              
  Lines       11811   11965     +154     
=========================================
+ Hits         4067    4104      +37     
- Misses       7744    7861     +117

Impacted Files	Coverage Δ
app/src/components/nav-bar/NavButton.js	0% <0%> (ø)	⬆️
app/src/components/ConnectPanel/RobotItem.js	0% <0%> (ø)	⬆️
...c/components/RobotSettings/AdvancedSettingsCard.js	0% <0%> (ø)	⬆️
app/src/pages/Robots/RobotSettings.js	0% <0%> (ø)	⬆️
app-shell/src/buildroot/index.js	0% <0%> (ø)	⬆️
app-shell/src/main.js	0% <0%> (ø)	⬆️
...pp/src/components/RobotSettings/InformationCard.js	0% <0%> (ø)	⬆️
app/src/shell/index.js	78.12% <0%> (+3.12%)	⬆️
app/src/http-api-client/server.js	79.2% <0%> (+3.25%)	⬆️
app/src/config/index.js	29.72% <0%> (+4.72%)	⬆️
... and 1 more

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 13d8128...2e8297b. Read the comment docs.

[btmorr]

🍘 Tested selector persistence and status endpoint with @mcous on #3869 . Didn't double-check that the logs are not sent up.