wiki pages, artists: fix normalization of other names.

Fix wiki pages and artists to normalize other names more consistently
and correctly.

For wiki pages, we strip leading / trailing / repeated underscores to
fix user typos, and we normalize to NFKC form to make search more consistent.

For artists, we allow leading / trailing / repeated underscores because
some artist names have these, and we normalize to NFC form because some
artists have weird names that would be lost by NFKC form. This does make
search less consistent.

app/models/wiki_page.rb

@@ -3,12 +3,12 @@ class WikiPage < ApplicationRecord
 
   META_WIKIS = ["list_of_", "tag_group:", "pool_group:", "howto:", "about:", "help:", "template:"]
 
-  before_validation :normalize_other_names
   before_save :update_dtext_links, if: :dtext_links_changed?
   after_save :create_version
 
   normalize :title, :normalize_title
   normalize :body, :normalize_text
+  normalize :other_names, :normalize_other_names
 
   validates :title, tag_name: true, presence: true, uniqueness: true, if: :title_changed?
   validates :body, presence: true, unless: -> { is_deleted? || other_names.present? }
@@ -153,12 +153,12 @@ class WikiPage < ApplicationRecord
     title.to_s.downcase.delete_prefix("~").gsub(/[[:space:]]+/, "_").squeeze("_").gsub(/\A_|_\z/, "")
   end
 
-  def normalize_other_names
-    self.other_names = other_names.map { |name| WikiPage.normalize_other_name(name) }.uniq
+  def self.normalize_other_names(other_names)
+    other_names.map { |name| normalize_other_name(name) }.uniq.reject(&:blank?)
   end
 
   def self.normalize_other_name(name)
-    name.unicode_normalize(:nfkc).gsub(/[[:space:]]+/, " ").strip.tr(" ", "_")
+    name.to_s.unicode_normalize(:nfkc).normalize_whitespace.gsub(/[[:space:]]+/, "_").squeeze("_").gsub(/\A_|_\z/, "")
   end
 
   def category_name