Use one instance of SerializationOptions in WikibaseLuaBindings

Creating a SerializationOptions object involves a bit of
overhead and performance cost, for example, creating a new
LanguageFallbackChain object for all the ~400 languages,
and validating language codes numerous times.

For one of my client pages with a bunch of lua usage,
LanguageWithConversion::validateLanguageCode was called
3967 times, taking a total of 452 ms second. Now it
is called 795 times (could be further optimized together with
parser function) and takes 93 ms.

LanguageFallbackChainFactory::newFromLanguageCode was called
2011 times, taking 271 ms. With this patch, it's now
called 403 times, 61 ms.

and a bunch of other slow methods are called much less.

* note that with full xdebug and memory tracing enabled, these numbers
are a bit slower than one would see otherwise.

Change-Id: I47a33011c8ac4e05bfd0922c15798f4fd981ef00
Merge "Use one instance of SerializationOptions in WikibaseLuaBindings"