[rush] Support direct to FS Cloud Cache

[dmichon-msft]

Summary

Provides the option for Cloud Cache providers to directly read the existing local cache entry when writing and write to a local file that will be ingested into the local cache when reading, rather than routing through an intermediary Buffer. This change is intended to reduce the memory footprint of the Rush process.

Details

Adds new optional APIs to ICloudBuildCacheProvider that read and write from a local file instead of taking a Buffer.

Since we use the native tar binary for packing and unpacking of archives, there is no benefit to maintaining the entire archive in memory.

How it was tested

Pending.

Impacted documentation

Documentation for implementing Cloud Build Cache Providers for Rush.