Make endpoint max request size more granularly configurable

[JordanMontgomery]

Goal

User story
As an infrastructure engineer managing a Fleet instance,
I want to granularly configure max request size on a per-endpoint basis
so that I can tune max request size to my fleet instance's needs.

Changes

Engineering

• Test plan is finalized
• Contributor API changes: TODO
• Feature guide changes: TODO
• Database schema migrations: TODO
• Load testing: TODO
• Pre-QA load test: TODO
• Load testing/osquery-perf improvements: TODO
• This is a premium only feature: Yes / No

ℹ️  Please read this issue carefully and understand it. Pay special attention to UI wireframes, especially "dev notes".

Risk assessment

• Requires testing in a hosted environment: TODO
• Requires load testing: TODO
• Risk level: Low / High TODO
• Risk description: TODO

Test plan

Make sure to go through the list and consider all events that might be related to this story, so we catch edge cases earlier.

• TODO
• TODO
• TODO

Testing notes

Confirmation

1. Engineer: Added comment to user story confirming successful completion of test plan.
2. QA: Added comment to user story confirming successful completion of test plan.