feat(gatsby-plugin-sharp): new srcSetAlwaysIncludeOriginal parameter for fluid()

[FineWolf]

Description

This PR add an additional argument to fluid() to allow to optionally remove the original size from the generated srcset.

From the added blurb in gatsby-plugin-sharp's README.md file.

By default, the original image is always added to the generated srcSet. However, if you
want to only generate sizes only up to the largest breakpoint defined in srcSetBreakpoints,
you can set srcSetAlwaysIncludeOriginal to false. Doing so will only generate images up
to the largest breakpoint or up to the original image size, whichever is the smallest.

This setting has also been exposed in gatsby-remark-images, and the appropriate changes have been made to the schema in gatsby-transformer-sharp.

This feature was added in order to support photography portfolios where we want to avoid at all costs to expose the original, full-resolution image. This thus allows the maintainers to safely use gatsby-plugin-sharp without doing any prior preprocessing of the image files.

Documentation

• This feature has been documented in the internal plugin README.md for gatsby-plugin-sharp.
• The new option has been documented in the internal plugin README.md for gatsby-remark-images.
• The default value of srcSetAlwaysIncludeOriginal (true) preserves the original behavior, thus avoiding a breaking change.
• Unit tests have been updated to test the additional parameter.

Related Issues

There are no related issues.

[ascorbic]

Thanks. I really dislike the current behaviour (and have removed it in the new resolver). I believe there's an issue open about this somewhere. Just one stylistic nit, and a merge conflict to fix

[FineWolf]

@ascorbic Requested changes have been made. Thanks!

[FineWolf]

Closing PR, no longer relevant.