Reduce indirection. PostSet is basically a collection of helper methods
for rendering the post index page. PostSetPresenter was a set of helper
methods for rendering the tag list on the post index page. These don't
need to be separated.
Make PostQueryBuilder apply aliases earlier, immediately after parsing
the search.
On the post index page there are multiple places where we need to apply
aliases:
* When running the search with PostQueryBuilder#build.
* When calculating the search count with PostQueryBuilder#fast_count.
* When calculating the related tags for the sidebar.
* When tracking missed searches and popular searches for Reportbooru.
* When looking up wiki excerpts.
Applying aliases after parsing ensures we only have to apply aliases
once for all of these things.
We also normalize the order of tags in searches and strip repeated tags.
This is so that we have consistent cache keys for fast_count.
* Fixes searches for aliased tags being counted as missed searches (fixes#4433).
* Fixes wiki excerpts not showing up when searching for aliased tags.
Several fixes for the "This tag is under discussion" notice on the post
index page:
* Fix the notice appearing for BURs that aren't pending.
* Fix the notice never going away because of the cache never expiring.
* List all topics when a tag is involved in multiple BURs.
* Link to the forum post instead of the forum topic (fix#4421).
* Optimization: don't check for BURs when the search isn't a simple
single tag search.
* Add a `tags` field to the bulk update requests table for tracking all
tags involved in the request (excluding tags in mass updates that are
negated/optional/wildcards). Known issue: doesn't handle tag type
prefixes in mass updates correctly (e.g. `mass update foo -> artist:bar`
doesn't detect the tag `bar`).
* Allow searching the /bulk_update_requests page by tags.
We don't really need to cache the notice here, but we do it anyway to
reduce queries on the post index page.
* Fix inconsistencies in how wiki pages were linked.
* Link directly to the wiki instead of to a title search that is expected
to redirect to the wiki.
Fineprint text was variously styled with `.info`, `.tn`, `.hint`, or
`.cost-footnote` css classes. Standardize on `.fineprint` instead. Use
`.hint` only for form hints and `.tn` only for <tn> tags in translation
notes.
Incidentally changes the font size of form hints to 0.8em (was 0.7em)
and the color of fineprint to #888 (was #AAA or #666).
* Move the limit:<n> / order:random metatag parsing from the controller
to the post set.
* Introduce `Tag.has_metatag?` and use it to parse these metatags
instead of using a regex (#2894).
