[JetBrains Backend Plugin] Allow specifying the test-repository when running launch-dev-server.sh

[felladrin]

Description

Allow passing a test-repository URL via parameter -r when running launch-dev-server.sh for JetBrains Backend Plugin development.

If the parameter is not passed, it will use the default test-repository: https://github.com/gitpod-io/spring-petclinic.

This PR also updates the plugin's path, which is now built with the name "gitpod-remote.zip".

Related Issue(s)

Resolves #10286

How to test

1. Open the branch of this PR in gitpod.io
2. Navigate to /workspace/gitpod/components/ide/jetbrains/backend-plugin
3. Run ./launch-dev-server.sh -r https://github.com/gitpod-io/.github
4. Confirm it has opened the test environment with https://github.com/gitpod-io/.github repository.
5. Stop the test environment and run rm -rf /workspace/test-repo.
6. Run ./launch-dev-server.sh
7. Confirm it has opened the test environment with https://github.com/gitpod-io/spring-petclinic repository.

Release Notes

NONE

Werft options:

• /werft with-preview

[andreafalzetti]

Works as advertised! In a next iteration we could try cleaning up the test-repo dir or, use a dynamic name (e.g. the name of the cloned repo) so that we don't have to manually remove the files.