media assets: add fix script to refresh metadata.

Add a script to go through every media asset and check the metadata
(width, height, duration, filesize, md5, EXIF metadata) and update it
if it's changed. This is necessary after upgrading ExifTool because the
metadata it returns may have changed.

script/fixes/123_refresh_media_metadata.rb

@@ -0,0 +1,34 @@
+#!/usr/bin/env ruby
+
+require_relative "base"
+
+with_confirmation do
+  condition = ENV.fetch("COND", "TRUE")
+  fix = ENV.fetch("FIX", "false").truthy?
+
+  MediaAsset.active.where(condition).find_each do |asset|
+    variant = asset.variant(:original)
+    media_file = variant.open_file
+
+    if media_file.nil?
+      puts ({ id: asset.id, error: "file doesn't exist", path: variant.file_path }).to_json
+      next
+    end
+
+    # Setting `file` updates the metadata if it's different.
+    asset.file = media_file
+    asset.media_metadata.file = media_file
+
+    old = asset.media_metadata.metadata_was.to_h
+    new = asset.media_metadata.metadata.to_h
+    metadata_changes = { added_metadata: (new.to_a - old.to_a).to_h, removed_metadata: (old.to_a - new.to_a).to_h }.compact_blank
+    puts ({ id: asset.id, **asset.changes, **metadata_changes }).to_json
+
+    if fix
+      asset.save! if asset.changed?
+      asset.media_metadata.save! if asset.media_metadata.changed?
+    end
+
+    media_file.close
+  end
+end