Support for S3 caching

Cody supports local cache, but I've found it quite pointless as the cache hits are extremely conditional on a number of factors.

[https://stackoverflow.com/a/59070807/4131237](https://stackoverflow.com/a/59070807/4131237)

Not from any public source, but these are some observations:

The cache will only be available if the build time is more than 5 minutes.

* Cache can be used if the new build is successfully placed on the same build host.

* Cache can be used if the new build is being run within 5-15 minutes of the last build. Cache may stay available based on the last build time with a max of 15 minutes.

* Despite builds exceeding 5 minutes, the cache may not always work probably due to build being placed on different build host.

* Additionally, in the case where the cache speeds up the new build to below 5 minutes, that build will not be cached resulting in subsequent miss.

It'd be great to allow configuring S3 cache with Cody by specifying the bucket name.

No files or tests are named. Start by tracing Cody's existing local cache configuration and how it generates AWS CodeBuild projects, then identify the configuration entry point for an S3 bucket. Done means Cody can accept a bucket name and use it for build caching, with cache behavior verified in an AWS CodeBuild project.

Written by the indexing model from the issue text.