[v2] add template userfunc with runner internals (like jobid, runid, etc)

[mimir-d]

depends on #135

New feature: add a template function that gives access to current jobid and runid. This is useful for plugins that specify storage paths for example, that should be parametrized by jobid. Proposal

"param": "sftp://server/logs/job_{{ contest jobid }}_run_{{ contest runid }}"