fix(gatsby): Support ESM-only gatsby-remark-* plugins

[LekoArts]

Description

When writing a local plugin (inside plugins)/using external plugin for gatsby-transformer-remark or remarkPlugins array of gatsby-plugin-mdx, this remark plugin didn't support being written in ESM.

This was due to no correct handling in the subPlugins validation. In addition to the resolve and options key of the plugin that a user might write in their gatsby-config, we're also adding module and modulePath to the object in the validation step. Previously, the module key was using require(). Now it uses await import.

Documentation

One expects it already works so no change needed.

Related Issues

[ch59936]