Add a new scenario to test basic Wiki functionalities

This will automatize the Wiki operations part of https://docs.google.com/spreadsheets/d/15AtBb6s2p_HvtUe5G9GUSc2ngt69X8dO-418zMuT4us/edit?ts=5b07999b#gid=0.

1. Create a project
2. Access its wiki
3. Create a page
4. Access the newly created page => assert that the page is created and contains the expected content
5. Modify the page => assert that the change is visible

Further improvements / Second iteration:

1. Clone the wiki
2. Modify the page locally
3. Push the change
4. Visit the wiki page => assert that the change is visible

changed title from Add a new scenario to test basic Wiki functionnalities to Add a new scenario to test basic Wiki functionalities

mentioned in issue #3 (closed)

changed the description

added [deprecated] Accepting merge requests label

changed weight to 4

mentioned in issue gitlab-com/migration#521 (closed)

added Community contribution label

I'm working on it.

@at.ramya Thanks!

assigned to @at.ramya

marked the checklist item Create a project as completed

marked the checklist item Access its wiki as completed

marked the checklist item Create a page as completed

marked the checklist item Create a page as incomplete

marked the checklist item Access the newly created page => assert that the page is created and contains the expected content as completed

marked the checklist item Create a page as completed

marked the checklist item Modify the page => assert that the change is visible as completed

marked the checklist item Clone the wiki as completed

marked the checklist item Modify the page locally as completed

marked the checklist item Push the change as completed

marked the checklist item Visit the wiki page => assert that the change is visible as completed

changed milestone to %11.1

added QA Quality labels