Make the sync client content encoding a tunable

[pmarkowsky]

This adds a new configuration option SyncClientContentEncoding which allows you to tweak the content encoding used by the sync client.

Currently this supports the following options:

Value	Expected Behavior
"" (default)	zlib compressed with Content-Encoding set to deflate
"gzip"	gzip compressed requests with Content-Encoding set to gzip
"deflate"	zlib compressed with Content-Encoding set to deflate
"none"	Content is not compressed at all

⚠️ This also removes the EnableBackwardsCompatibleContentEncoding config option.

Testing

Tested with a hacked up version of moroz.

Headers when SyncClientContentEncoding is set to gzip

POST /v1/santa/preflight/<machine_id>
Host: santa:8080
Content-Type: application/json
Connection: keep-alive
Accept: */*
Content-Encoding: gzip
User-Agent: santactl-sync/9999.1.1
Content-Length: 402
Accept-Language: en-US,en;q=0.9
Accept-Encoding: gzip, deflate

Headers when SyncClientContentEncoding is set to None

POST /v1/santa/preflight/<machine_id>
Host: santa:8080
Content-Type: application/json
Connection: keep-alive
Accept: */*
User-Agent: santactl-sync/9999.1.1
Content-Length: 536
Accept-Language: en-US,en;q=0.9
Accept-Encoding: gzip, deflate