fix: correct gin embedder indices.
Move electron extra embedders to the end of the enum so they do not
interfere with chromium embedders indices.
Also use kEmbedderBlinkTag directly in its index calculation without
adding extra indices from other tags.
Co-authored-by: trop[bot] <37223003+trop[bot]@users.noreply.github.com>
Co-authored-by: Marek Haranczyk <marek@openfin.co>
179fde9278