Show tenant earlier in inspect output (#191)

This PR changes the way inspect displays the tenant.
Previously, the tenant was appended at the end of the string, e.g.:

`#<User id: 1, email: "[email protected]", tenant="acme">
`

With this change, the tenant is injected immediately after the class
token, making it one of the first pieces of information shown:

`#<User tenant: "acme", id: 1, email: "[email protected]">`

Why?

In classes with many attributes, having the tenant all the way at the
end makes it harder to notice. Since the tenant is a critical piece of
context, showing it right after the class name makes it more visible and
improves readability.

I also updated the tests to reflect this new behavior.

Author: flavorjones

lib/active_record/tenanted/tenant.rb

@@ -17,7 +17,9 @@ def cache_key
       end
 
       def inspect
-        tenant ? super.sub(/>$/, ", tenant=#{tenant.inspect}>") : super
+        return super unless tenant
+
+        super.sub(/\A#<\S+ /, "\\0tenant: #{tenant.inspect}, ")
       end
 
       def to_global_id(options = {})

test/unit/tenant_test.rb

@@ -1194,7 +1194,7 @@
             User.create!(email: "[email protected]")
           end
 
-          assert_match(/, tenant="foo">$/, user.inspect)
+          assert_match(/\A#<User tenant: "foo", id:/, user.inspect)
         end
       end
     end