Gzip: Add decompression handler

[And1sS]

🔧 Type of changes

• new bid adapter
• bid adapter update
• new feature
• new analytics adapter
• new module
• module update
• bugfix
• documentation
• configuration
• dependency update
• tech debt (test coverage, refactorings, etc.)

✨ What's the context?

Added ability to decompress request body when gzip query param is equal to 1 or true as requested here: prebid/prebid-server#4474.

PR also replaces auction.max-request-size with server.max-body-size setting that configures application-wide max body size for all endpoints.

🧠 Rationale behind the change

prebid/prebid-server#4474

🧪 Test plan

Unit tests

🏎 Quality check

• Are your changes following our code style guidelines?
• Are there any breaking changes in your code?
• Does your test coverage exceed 90%?
• Are there any erroneous console logs, debuggers or leftover code in your changes?