This commit makes some fundamental changes to how hashtag cooking and
icon generation works in the new experimental hashtag autocomplete mode.
Previously we cooked the appropriate SVG icon with the cooked hashtag,
though this has proved inflexible especially for theming purposes.
Instead, we now cook a data-ID attribute with the hashtag and add a new
span as an icon placeholder. This is replaced on the client side with an
icon (or a square span in the case of categories) on the client side via
the decorateCooked API for posts and chat messages.
This client side logic uses the generated hashtag, category, and channel
CSS classes added in a previous commit.
This is missing changes to the sidebar to use the new generated CSS
classes and also colors and the split square for categories in the
hashtag autocomplete menu -- I will tackle this in a separate PR so it
is clearer.
0b3cf83e3c