Add PHP and PHP + MySQL Che-7 stacks with samples

[svor]

What does this PR do?

Adds PHP and PHP + MySQL Che-7 stacks which include next plugins:

• php-intelephense
• php debug

Adds samples:

• Hello World
• Laravel Real World example App
• Symfony demo application
• Sample CRUD PHP+MySQL

What issues does this PR fix or reference?

#13307

[svor]

ci-test

[sleshchenko]

LGTM
Just wondering if we need the corresponding devfiles in Che Devfile Registry, maybe a separate issue to port them. @l0rd WDYT?

[che-bot]

Results of automated E2E tests of Eclipse Che Multiuser on OCP:
Build details
Test report
docker image: eclipseche/che-server:13434
https://github.com/orgs/eclipse/teams/eclipse-che-qa please check this report.

[tolusha]

ci-test

[l0rd]

@sleshchenko @svor yes it would be better to start contributing to the devfile-registry directly. But that can be done on a separate PR as well.

[che-bot]

Results of automated E2E tests of Eclipse Che Multiuser on OCP:
Build details
Test report
docker image: eclipseche/che-server:13434
https://github.com/orgs/eclipse/teams/eclipse-che-qa please check this report.

[SkorikSergey]

Selenium tests execution on Eclipse Che Multiuser on OCP (https://ci.codenvycorp.com/job/che-pullrequests-test-ocp/1819//Selenium_20tests_20report/) doesn't show any regression against this Pull Request.