Load extension parameters via simple ContextInitializer instead of EnvironmentLoader.

[kolotaev]

Currently it's not possible to extend SoapContext in custom any FeatureContext.

It allows us to extend SoapContext in custom FeatureContexts. Otherwise EnvironmentLoader always add SoapContext steps on every test thus causing potential steps duplication in SoapContext and its descendant classes.

[BR0kEN-]

@kolotaev, if you want to remove the environment loader then the PR must have tests and usage examples added to the documentation since autoloading of contexts will no longer happen.

[kolotaev]

@BR0kEN-, thanks! I've added a behat test and a use-case example that uses extended SOAPContext.

If you apply commit that adds tests to the current upstream's master branch you'll see the following error:

Step "I am working with SOAP service WSDL :wsdl" is already defined in Behat\SoapExtension\Context\Bootstrap\ExtendedSoapContext::iAmWorkingWithSoapServiceWSDL()
Behat\SoapExtension\Context\Bootstrap\ExtendedSoapContext::iAmWorkingWithSoapServiceWSDL()
Behat\SoapExtension\Context\SoapContext::iAmWorkingWithSoapServiceWSDL()

[kolotaev]

@BR0kEN-, sorry for pinging you once again, but is it possible to review and merge this PR and add it to a new release? Our production code tests depend on it. Otherwise, I'd appreciate if you point out what should be adjusted in the PR so that I can amend it. Thank you in advance!

[BR0kEN-]

We need @asgorobets here.