MR command: check git push successful before running glab mr command

[waako]

Problem

When running ddev mr, the git push trigger pre-push hooks and sanity-check command.
If sanity check fails or aborted, currently the command continues with the glab mr create command, if branch not pushed at all this will error.

Reproduce

In a project with issues such as: views.view.files.yml is missing 'operations' and feature branch not yet pushed to GitLab.

• ddev mr
• Sanity-check fail. Continue pushing anyway?: enter N
• now offers: ? Choose a template: for Gitlab MR creation, which will fail as no branch pushed.

Proposition:

use set -e to exit command at first failure, easiest approach for now.