Add end-to-end tests for edit posts page

[talldanwp]

It'd be great to explore adding more e2e tests for WordPress, and the edit posts/all posts page seems like a good place to start.

I've written a few of these in Gutenberg and I'd like to work on adding some for core.

## Description

Fixes https://core.trac.wordpress.org/ticket/49507

Adds e2e tests for the edit posts page. This is currently a work in progress and not quite ready for review.

Sequel to #200, fixes element targeting issues in some of the tests.

Trac ticket: https://core.trac.wordpress.org/ticket/49507

[prbot]

​azaozz commented on ​PR #200:

Should this be closed in favour of ​https://github.com/WordPress/wordpress-develop/pull/1089? Thinking 1089 is ready to go in, all tests green :)

[prbot]

​talldan commented on ​PR #200:

Yep!

[prbot]

​JustinyAhin commented on ​PR #1089:

I've run the tests, and they work as expected.

@tellthemachines I was wondering, does it make sense to add a README to the e2e folder with information about how to run the test, how to enable headless mode for the tests for instance?

Also, what does this needs to get merged?

Trac ticket: https://core.trac.wordpress.org/ticket/49507

[prbot]

​talldan commented on ​PR #1089:

There's a README over here @JustinyAhin - ​https://github.com/WordPress/wordpress-develop/pull/1451.

[prbot]

​hellofromtonya commented on ​PR #1089:

@tellthemachines @talldan Is this PR ready for commit? Does it overlap any of the work that @JustinyAhin is doing?

[prbot]

​tellthemachines commented on ​PR #1089:

@hellofromtonya yup, this one's ready to go. It doesn't overlap with Justin's PRs as this is specific to the posts screen and Justin has been focusing on other screens so far.