Environment variable for user who triggered build

These are the environment variables we can use now: https://confluence.atlassian.com/bitbucket/environment-variables-794502608.html

I'd also like to have access to the person who triggered the Pipeline, either the Git user who committed/pushed the changes, or the Bitbucket user who manually triggered the Pipeline.

Ideally this would be provided in the format Full name <email@address.com>, similar to Git.

Original request

This ticket also requested the Git commit short hash, but that is easily retrievable either via git directly (git log --format=%h -n1) or by trimming down the BITBUCKET_COMMIT env var (echo $BITBUCKET_COMMIT | cut -c1-7).