Search backend: add standardized tracing for jobs

Created by: camdencheek

This adds some utility functions for tracing search jobs. They live in a new subpackage of internal/search/job because jobs cannot import the job package because the job package imports all the jobs for pretty printing (we could use some dep inversion here).

Right now, these functions are very minimal. They basically just set the trace title to job.Name() and set the error and alert on job completion. However, having one place to handle all this will allow us to quickly add some richness to our traces with things like job args, logs for events, total events streamed through the job, etc.

Test plan

Manually tested locally. See screenshot and note the new alert tag.