Removes emoji code conversion from the page and shortcode parsers. Emoji
codes in markdown are now passed to Goldmark, where the goldmark-emoji
extension converts them to decimal numeric character references.
This disables emoji rendering for the alternate content formats: html,
asciidoc, org, pandoc, and rst.
Fixes #7332
Fixes #11587
Closes #11598
We could reset and rerun it on server rebuilds, but that report needs a full build to make sense.
Also clean up the config vs flags in this area: Make all config settings match the flags e.g. `printPathWarnings`, but set up aliases for the
old.
Fixes #11187
Primary motivation is documentation, but it will also hopefully simplify the code.
Also,
* Lower case the default output format names; this is in line with the custom ones (map keys) and how
it's treated all the places. This avoids doing `stringds.EqualFold` everywhere.
Closes #10896
Closes #10620
