Language injection for CSS, XPath, JSON and DQL

[King2500]

This adds automatic language injection for method parameters for the following languages:

• CSS Selectors and XPath in CssSelector and DomCrawler component
• JSON for JsonResponse
• DQL for Doctrine Queries (Parameter for createQuery and $dql = assignments) (JetBrains added official DQL Support since PhpStorm 2018.3, but you had to inject manually or use <<<DQL heredoc)

Advantages:

• full syntax highlight
• syntax error check
• autocompletion

CSS Selectors:

and

XPath:

DQL:

I also wrote tests for these injections.

One question for me remains:
Should we add checkboxes to disable these languages injections (by each language) in settings dialog?

[King2500]

I did test the feature locally in 2018.3, 2019.1 and 2019.1.1 Preview

[King2500]

Maybe add Yaml injection for Yaml::parse('yaml here')

(Edit: I rethought this and think it's not very common to have Yaml::parse called with literals directly, so it's not worth injecting this language automatically.)

[cedricziel]

I think we should make the DQL plugin mandatory. Both from a usability POV, but also because we dont currently check whether the plugin is installed. WDYT?

Suggested change

	<depends optional="true">com.jetbrains.php.dql</depends>
	<depends>com.jetbrains.php.dql</depends>

[King2500]

IntelliJ is smart enough to handle unknown languages (i.e. DQL plugin is not installed), when calling registrar.startInjecting(language). So there is no need to check that explicitly.

I'm not sure if it is a good idea to have this dependency mandatory. I think there are a lot people out there who only use some Symfony components and thus have the Symfony plugin installed, but don't need/use Doctrine/DQL.

[King2500]

As far as I can see, "DQL Support" is bundled by default in PhpStorm. So this affects only people with IntelliJ IDEA Ultimate who have installed PHP plugin manually.