feat: enable prebuilds via persisting bazel/blaze cache

[ghuntley]

Description

Bazel/Blaze by default stores its build cache in a place where Gitpod does not persist thus meaning Blaze/Bazel does not work with prebuilds.

Related Issue(s)

L10 of https://github.com/carbon-language/carbon-lang/compare/trunk...gitpod-forks:carbon-lang:devenv/gitpod?expand=1#diff-454eff0561fdbb1cdf08bef7a76ddf0f82c65fca08a150c43650f5098ecf7118R10 should not be required.

How to test

Tests are included but I have not tested running a workspace and am raising pull-request to trigger a CI job.

Release Notes

feat: enable prebuilds via persisting bazel/blaze cache

Documentation

[gitpod-io[bot]]

[gitpod-staging[bot]]

[jenting]

It needs rebase to main branch.

[jenting]

I rebase it.

[kylos101]

Tests are included but I have not tested running a workspace and am raising pull-request to trigger a CI job.

Hi @ghuntley :wave: ,

To test, I recommend:

1. Opening a Gitpod from this PR
2. ./build-combo.sh full <-- this will take a bit, and is caching in your workspace
3. push the image from your workspace's local registry to Docker Hub
4. set the image (now on docker hub) as a base image for your repo where you want to test prebuilds
5. test prebuilds