Feature/env test path

[mwaltonen]

The Issue

Some environments do not allow site developers to save data to the root of the project. For instance, multisite environments on a common Drupal deployment where each site developer can only maintains the code within their site folder (e.g. web/sites/my.site.com.

Additionally, this will address some naming mismatches throughout the add-on (backstop, backstopjs, ddev-backstopjs, etc.)

How This PR Solves The Issue

Using ddev's environment variables for containers, the custom tests path can be saved to the project and updates from this add-on can still be consumed without revisiting configuration. This also allows the developer to save their backstop data to a custom place and still be able to share it with their team.

Manual Testing Instructions

1. Confirm standard deployment works and a testing report is generated and viewable

ddev add-on get https://github.com/mmunz/ddev-backstopjs/tarball/refs/pull/27/head
ddev restart
ddev backstop init
ddev backstop reference
ddev backstop test
ddev backstop-results

2. Move the testing folder a confirm everything still works as expected

ddev stop
ddev dotenv set .ddev/.env.backstopjs --backstopjs-testdir tests-new/backstop
mv tests tests-new
ddev start
ddev backstop test
ddev backstop-results

3. Move to a new path, but fail to move the existing tests dir or create a new dir. Confirm ownership is updated to match your username.

ddev stop
ddev dotenv set .ddev/.env.backstopjs --backstopjs-testdir tests-bad/backstop
ddev start
stat -c '%U:%G' tests-bad/backstop

4. Confirm everything still works as expected after the permissions fix

ddev backstop init
ddev backstop reference
ddev backstop test
ddev backstop-results

5. Move to a new path, but fail to move the existing tests dir or create a new dir. Turn off auto repair to confirm user feedback is clear.

ddev stop
ddev dotenv set .ddev/.env.backstopjs --backstopjs-testdir tests-bad2/backstop
ddev dotenv set .ddev/.env.backstopjs --backstopjs-allow-perm-repair false
ddev start

6. Clean up and confirm everything still works as expected.

ddev stop
ddev dotenv set .ddev/.env.backstopjs --backstopjs-testdir tests/backstop
ddev dotenv set .ddev/.env.backstopjs --backstopjs-allow-perm-repair true
sudo rm -rf tests*
mkdir -p tests/backstop
ddev start
ddev backstop init
ddev backstop reference
ddev backstop test
ddev backstop-results
ddev poweroff