Reorder methods in EntityViewBuilder

The order of methods in EVB was already a bit random, but #2099131: Use #pre_render pattern for entity render caching disconnected it even more from the actual execution flow.
Reordering was left for a followup to make diffs easier to review over there.

Patch reorders EVB like so:

// Instantiation
public function __construct();
public static function createInstance();

// Main API entry point & initital build
public function view();
public function viewMultiple();
protected function getBuildDefaults();

// #pre_render steps
public function build();
public function buildMultiple();
public function buildComponents();
protected function alterBuild();

// Cache management
public function getCacheTag();
public function resetCache();
protected function isViewModeCacheable();

// "Standalone field render" API
public function viewField();
public function viewFieldItem();

(yeah, that's the kind of patches I write these days :-/)

Nitpick : arguably, isViewModeCacheable() could be inlined within getBuildDefaults() ?