Revert "chore(*): Use new createContentDigest helper (#8992)"

[KyleAMathews]

This reverts commit c91d110 and PR #8992

We can't introduce a new file to the core gatsby package and then also update packages to use it without having a fallback as people often update/install packages without updating core.

[DSchau]

If we do do this--we need to ensure we update the peerDependency on gatsby.

Also isn't the path gatsby/dist/utils? I think that's more of the issue here--no version of Gatsby would have these afaik.

https://unpkg.com/gatsby@2.3.26/

[KyleAMathews]

There was a new file added https://github.com/gatsbyjs/gatsby/pull/8992/files#diff-7b0d4dc1ad15094456fc37848d323bb1

The problem is that npm doesn't enforce peerDependencies so while there'd be a warning, most people wouldn't see that and not understand why upgrading/installing a package broke things.

[KyleAMathews]

Another problem @pieh just pointed out is that the utils.js file wasn't published due to https://github.com/gatsbyjs/gatsby/blob/master/packages/gatsby/package.json#L147-L152

[Olanetsoft]

I still get the same error how do I fix it, please?