gitrest: Allow enforcing file size write limits

[znewton]

Description

For reliability, it is important that we can prevent summary uploads to Redis that are too large to safely handle. This PR adds the functionality and configuration option to limit writeFile size in RedisFs.

Additionally, we need to protect the service from writing too large of files. After a file is written in compressed format, it is difficult to know how large it will be when unpacked. In severe cases, unpacking a too-compressed summary blob can kill the service by using too much memory. This PR adds write limits for the default FS as well.

[znewton]

Re-opening with expanded scope