Allow select statement node's initializer takes a table

Like other statement nodes does, related to 333f9b32.

activerecord/lib/arel/nodes/select_core.rb

@@ -6,9 +6,9 @@ module Arel # :nodoc: all
       attr_accessor :projections, :wheres, :groups, :windows, :comment
       attr_accessor :havings, :source, :set_quantifier, :optimizer_hints
 
-      def initialize
+      def initialize(relation = nil)
         super()
-        @source = JoinSource.new nil
+        @source = JoinSource.new(relation)
 
         # https://ronsavage.github.io/SQL/sql-92.bnf.html#set%20quantifier
         @set_quantifier  = nil

activerecord/lib/arel/nodes/select_statement.rb

@@ -6,9 +6,9 @@ module Arel # :nodoc: all
       attr_reader :cores
       attr_accessor :limit, :orders, :lock, :offset, :with
 
-      def initialize(cores = [SelectCore.new])
+      def initialize(relation = nil)
         super()
-        @cores          = cores
+        @cores          = [SelectCore.new(relation)]
         @orders         = []
         @limit          = nil
         @lock           = nil

activerecord/lib/arel/select_manager.rb

@@ -8,9 +8,8 @@ module Arel # :nodoc: all
 
     def initialize(table = nil)
       super()
-      @ast = Nodes::SelectStatement.new
+      @ast = Nodes::SelectStatement.new(table)
       @ctx = @ast.cores.last
-      from table
     end
 
     def initialize_copy(other)