Use quote methods rather than single quotes to identifiers in SQL

Related rails#29612, rails#26784, rails#24950.

Author: kamipo

activerecord/lib/active_record/connection_adapters/postgresql/schema_dumper.rb

@@ -91,7 +91,7 @@ def prepare_column_options(column)
               spec = { type: schema_type(column).inspect }.merge!(spec)
             end
 
-            spec[:enum_type] = "\"#{column.sql_type}\"" if column.enum?
+            spec[:enum_type] = column.sql_type.inspect if column.enum?
 
             spec
           end

activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb

@@ -576,24 +576,24 @@ def drop_enum(name, values = nil, **options)
 
       # Rename an existing enum type to something else.
       def rename_enum(name, **options)
-        to = options.fetch(:to) { raise ArgumentError, ":to is required" }
+        new_name = options.fetch(:to) { raise ArgumentError, ":to is required" }
 
-        exec_query("ALTER TYPE #{quote_table_name(name)} RENAME TO #{to}").tap { reload_type_map }
+        exec_query("ALTER TYPE #{quote_table_name(name)} RENAME TO #{quote_table_name(new_name)}").tap { reload_type_map }
       end
 
       # Add enum value to an existing enum type.
       def add_enum_value(type_name, value, **options)
         before, after = options.values_at(:before, :after)
         sql = +"ALTER TYPE #{quote_table_name(type_name)} ADD VALUE"
         sql << " IF NOT EXISTS" if options[:if_not_exists]
-        sql << " '#{value}'"
+        sql << " #{quote(value)}"
 
         if before && after
           raise ArgumentError, "Cannot have both :before and :after at the same time"
         elsif before
-          sql << " BEFORE '#{before}'"
+          sql << " BEFORE #{quote(before)}"
         elsif after
-          sql << " AFTER '#{after}'"
+          sql << " AFTER #{quote(after)}"
         end
 
         execute(sql).tap { reload_type_map }
@@ -608,7 +608,7 @@ def rename_enum_value(type_name, **options)
         from = options.fetch(:from) { raise ArgumentError, ":from is required" }
         to = options.fetch(:to) { raise ArgumentError, ":to is required" }
 
-        execute("ALTER TYPE #{quote_table_name(type_name)} RENAME VALUE '#{from}' TO '#{to}'").tap {
+        execute("ALTER TYPE #{quote_table_name(type_name)} RENAME VALUE #{quote(from)} TO #{quote(to)}").tap {
           reload_type_map
         }
       end