[POC] Multiple Background Examples support

[dpakach]

Add support for multiple background examples in a feature.

For eg.

Feature: Users sync

  Background:
    Given these users have been created with default attributes and without skeleton files:
    | username |
    | user0    |
    | user1    |

    Examples:
      | ocs-api-version | ocs-status-code |
      | 1               | 100             |

    @OCSv2
    Examples:
      | ocs-api-version | ocs-status-code |
      | 2               | 200             |

  Scenario Outline: Trying to sync a user when there is no external user backend
    Given using OCS API version "<ocs-api-version>"
    When the administrator tries to sync user "user0" using the OCS API
    Then the HTTP status code should be "200"
    And the OCS status code should be "<ocs-status-code>"
    And the OCS status message should be ""

  @TestAlsoOnExternalUserBackend
  Scenario Outline: Trying to sync a user as another user which does not exist
    Given using OCS API version "<ocs-api-version>"
    When user "user20" tries to sync user "user1" using the OCS API
    Then the HTTP status code should be "401"
    And the OCS status code should be "997"
    And the OCS status message should be "Unauthorised"

In this above example, running without any tags will just run both outlines with both tables from the background.

But if we run with tag @OCSv2 then both outlines will run with only the second table from the background.

[jasson99]

LGTM

[Talank]

LGTM 👍