DEV: Correctly tag heredocs (#16061)

This allows text editors to use correct syntax coloring for the heredoc sections.

Heredoc tag names we use:

languages: SQL, JS, RUBY, LUA, HTML, CSS, SCSS, SH, HBS, XML, YAML/YML, MF, ICS
other: MD, TEXT/TXT, RAW, EMAIL

lib/tasks/javascript.rake

@@ -22,7 +22,7 @@ def html_for_section(group)
     "    {{replace-emoji \":#{icon['name']}:\" (hash lazy=true#{class_attr})}}"
   end
 
-  <<~SECTION
+  <<~HTML
     <div class="section" data-section="#{group["name"]}">
       <div class="section-header">
         <span class="title">{{i18n "emoji_picker.#{group["name"]}"}}</span>
@@ -31,14 +31,14 @@ def html_for_section(group)
         #{icons.join("\n").strip}
       </div>
     </div>
-  SECTION
+  HTML
 end
 
 def write_template(path, task_name, template)
-  header = <<~HEADER
+  header = <<~JS
     // DO NOT EDIT THIS FILE!!!
     // Update it by running `rake javascript:#{task_name}`
-  HEADER
+  JS
 
   basename = File.basename(path)
   output_path = "#{Rails.root}/app/assets/javascripts/#{path}"
@@ -50,10 +50,10 @@ def write_template(path, task_name, template)
 end
 
 def write_hbs_template(path, task_name, template)
-  header = <<~HEADER
+  header = <<~HBS
   {{!-- DO NOT EDIT THIS FILE!!! --}}
   {{!-- Update it by running `rake javascript:#{task_name}` --}}
-  HEADER
+  HBS
 
   basename = File.basename(path)
   output_path = "#{Rails.root}/app/assets/javascripts/#{path}"
@@ -244,11 +244,11 @@ task 'javascript:update_constants' => :environment do
   groups_json = JSON.parse(File.read("lib/emoji/groups.json"))
 
   emoji_buttons = groups_json.map do |group|
-    <<~BUTTON
+    <<~HTML
 			<button type="button" data-section="#{group["name"]}" {{action onCategorySelection "#{group["name"]}"}} class="btn btn-default category-button emoji">
 				 {{replace-emoji ":#{group["tabicon"]}:"}}
 			</button>
-    BUTTON
+    HTML
   end
 
   emoji_sections = groups_json.map { |group| html_for_section(group) }