Show results from docker image scan in the merge request widget

Same as https://gitlab.com/gitlab-org/gitlab-ee/issues/3775 but for https://gitlab.com/gitlab-org/gitlab-ee/issues/3724

Design

Sucess icon:

• No vulnerabilities
• Only approved vulnerabilities

Warning icon:

• Any unapproved vulnerabilities found

Not found icon:

• if test is not available/cannot be loaded, will be tackled in a separate issue as currently it will use failed status icon: https://gitlab.com/gitlab-org/gitlab-ee/issues/4316

loading icon:

• when loading results

copy:

No vulnerabilities:

No vulnerabilities were found

No unapproved vulnerabilities

Found 1 approved vulnerability | Found 20 approved vulnerabilities

Only unapproved vulnerabilities

Found 1 vulnerability | Found 10 vulnerabilities

Both

Found 2 vulnerabilities, of which 1 is approved | Found 3 vulnerabilities, of which 1 is approved