[StaticSite]: Please make 'deployId' public

[iDVB]

Currently, StaticSite makes this.deployId private.

However, is it was made public, people could pass this value into other constructs that need to know which bucket key/directory is the public/deployed one.

Eg. We have a Lambda@Edge that processes a file in the root of the deploy bucket (usually the root) called _redirects. Since StaticSite moves this down into a dynamic key deploy-[hash] it has rendered our router inoperable.

WithdeployId we plan to create a custom CF header that can pass this value into our edge function which will fix the issue.