chore(gatsby-plugin-image): Add peerDependenciesMeta

[aaronadamsCA]

Description

• Specify gatsby-plugin-image optional peer dependencies.
• Specify gatsby-source-shopify peer dependency on Gatsby.

Documentation

No docs required.

Note that the docs indicate gatsby-plugin-sharp is required, but this PR still marks it as optional. That's because it's possible to install and import from the gatsby-plugin-image package without actually loading the plugin in gatsby-config.js.

Related Issues

Fixes #34685.

[LekoArts]

That's because it's possible to install and import from the gatsby-plugin-image package without actually loading the plugin in gatsby-config.js.

But that's not what people should do. Using the plugin without having it in the plugins array will break behavior in the build and thus it's required to have it defined. So I'd say gatsby-plugin-sharp shouldn't be optional.

[aaronadamsCA]

Using the plugin without having it in the plugins array will break behavior in the build and thus it's required to have it defined.

Sorry if I was unclear - our use case here is for importing from gatsby-plugin-image into a UI library, as a transitive dependency of a Gatsby site.

• UI package imports GatsbyImage from gatsby-plugin-image
• Gatsby themes import UI package
• Gatsby sites import Gatsby themes

IMO this is already valid, so we just suppress the warnings using packageExtensions in .yarnrc.yml to define peerDependenciesMeta on gatsby-plugin-image ourselves. I just wanted to contribute that back, since it should help anyone else with a large repo.