Close revoke deploy token modal on escape keypress

What does this MR do?

Closes revoke deploy token modal on escape keypress.

Are there points in the code the reviewer needs to double check?

Check if tabindex in https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/20347/diffs#7893afa62e49be450e2d95758271bcb35817d3f4_2_1 uses the best possible value.

Screenshots (if relevant)

Revoke deploy token

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Tests added for this feature/bug
• Conform by the code review guidelines
  • Has been reviewed by a UX Designer
  • Has been reviewed by a Frontend maintainer

What are the relevant issue numbers?

#45850 (closed).