Add QuickEdit Javascript tests

Problem/Motivation

Quick edit currently has no javascript tests.

#2919373: Prevent Settings Tray functionality for blocks that have configuration overrides introduced a test that introduced test failures on PHP 5.5 & PostgreSQL 9.1:
https://www.drupal.org/pift-ci-job/864394
https://www.drupal.org/pift-ci-job/864395

These failures are actually coming from Quick Edit ajax calls. Probably no other test actually is having these

Drupal\Tests\settings_tray\FunctionalJavascript\SettingsTrayBlockFormTest::testOverriddenConfigurationRemoved
Zumba\GastonJS\Exception\JavascriptError: One or more errors were raised in the Javascript code on the page.
If you don't care about these errors, you can ignore them by
setting js_errors: false in your Poltergeist configuration (see documentation for details).
AjaxError:
An AJAX HTTP request terminated abnormally.
Debugging information follows.
Path: /subdirectory/quickedit/attachments
StatusText: error
ResponseText:
ReadyState: 0
AjaxError:
An AJAX HTTP request terminated abnormally.
Debugging information follows.
Path: /subdirectory/quickedit/attachments
StatusText: error
ResponseText:
ReadyState: 0
at http://php-apache-jenkins-php5-5-postgres9-1-2809/subdirectory/core/misc... in error
at http://php-apache-jenkins-php5-5-postgres9-1-2809/subdirectory/core/misc... in complete
at http://php-apache-jenkins-php5-5-postgres9-1-2809/subdirectory/core/asse... in i
at http://php-apache-jenkins-php5-5-postgres9-1-2809/subdirectory/core/asse... in fireWith
at http://php-apache-jenkins-php5-5-postgres9-1-2809/subdirectory/core/asse... in A
at http://php-apache-jenkins-php5-5-postgres9-1-2809/subdirectory/core/asse...
at :0 in openUrl
at phantomjs://platform/webpage.js:281 in open
at phantomjs://code/web_page.js:71
at phantomjs://code/browser.js:202 in visit
at phantomjs://code/browser.js:1272 in serverRunCommand
at phantomjs://code/poltergeist.js:38 in serverRunCommand
at phantomjs://code/server.js:76 in handleRequest
at phantomjs://code/server.js:22

/var/www/html/vendor/jcalderonzumba/gastonjs/src/Browser/BrowserBase.php:119
/var/www/html/vendor/jcalderonzumba/gastonjs/src/Browser/BrowserBase.php:99
/var/www/html/vendor/jcalderonzumba/gastonjs/src/Browser/BrowserNavigateTrait.php:19
/var/www/html/vendor/jcalderonzumba/mink-phantomjs-driver/src/NavigationTrait.php:15
/var/www/html/vendor/behat/mink/src/Session.php:148
/var/www/html/core/tests/Drupal/Tests/BrowserTestBase.php:682
/var/www/html/core/modules/system/tests/src/FunctionalJavascript/OffCanvasTestBase.php:16
/var/www/html/core/modules/settings_tray/tests/src/FunctionalJavascript/SettingsTrayBlockFormTest.php:666

FAILURES!
Tests: 26, Assertions: 733, Errors: 1.

We need to actually test Quick edit separately so that if other modules want to test with Quick Edit on they don't have to worry that there will be problems.

Proposed resolution

Add javascript tests.

Remaining tasks

User interface changes

API changes

Data model changes